Implementation of stimuli with millisecond timing accuracy in online experiments

Online experiments are growing in popularity. This study aimed to determine the timing accuracy of web technologies and investigate whether they can be used to support high temporal precision psychology experiments. A dynamic sinusoidal grating and flashes were produced by setInterval, CSS3, and requestAnimationFrame (hereafter, rAF) technologies. They were run at normal or real-time priority processing in Chrome, Firefox, Edge, and Internet Explorer on Windows, macOS, and Linux. Timing accuracies were compared with that of Psychtoolbox which was chosen as gold standard. It was found that rAF with real-time priority had the best timing accuracy compared to the other web technologies and had a similar timing accuracy as Psychtoolbox in traditional experiments in most cases. However, rAF exhibited poor timing accuracy on Linux. Therefore, rAF can be used as technical basis for accuracy of millisecond timing sequences in online experiments, thereby benefiting the psychology field.

Distress tolerance and cannabis craving: The impact of laboratory-induced distress

Low levels of distress tolerance have been identified as an important vulnerability factor for negative cannabis outcomes. The current study is the first known experimental manipulation of state distress to test whether distress tolerance interacts with state distress to predict the urge to use cannabis. Current cannabis users (N = 126; 88.9% with cannabis use disorder; 54.0% non-Hispanic Caucasian) were randomly assigned to a distress task condition or neutral (reading) task condition. Participants in the 2 conditions did not differ on distress tolerance, negative affect (NA), or craving at baseline. The distress tolerance × condition interaction significantly predicted task NA, such that low (but not high) distress tolerance was related to greater state NA throughout the task. The distress tolerance × condition interaction significantly predicted cannabis craving during the task, such that the distress condition was related to greater cannabis craving at lower (but not higher) levels of distress tolerance. In the distress condition, those who endorsed coping motives during the task reported lower distress tolerance. Together these findings suggest that individuals with lower distress tolerance experienced greater NA during a laboratory-induced distress and reported greater cannabis craving when NA was greatest during the task. This experimental study adds to a growing, but limited, literature implicating lower levels of distress tolerance to the maintenance and relapse of cannabis use. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Translating experimental paradigms into individual-differences research: Contributions, challenges, and practical recommendations

Psychological science has long been cleaved by a fundamental divide between researchers who experimentally manipulate variables and those who measure existing individual-differences. Increasingly, however, researchers are appreciating the value of integrating these approaches. Here, we used visual attention research as a case-in-point for how this gap can be bridged. Traditionally, researchers have predominately adopted experimental approaches to investigating visual attention. Increasingly, however, researchers are integrating individual-differences approaches with experimental approaches to answer novel and innovative research questions. However, individual differences research challenges some of the core assumptions and practices of experimental research. The purpose of this review, therefore, is to provide a timely summary and discussion of the key issues. While these are contextualised in the field of visual attention, the discussion of these issues has implications for psychological research more broadly. In doing so, we provide eight practical recommendations for proposed solutions and novel avenues for research moving forward.

PredPsych: A toolbox for predictive machine learning-based approach in experimental psychology research

Recent years have seen an increased interest in machine learning-based predictive methods for analyzing quantitative behavioral data in experimental psychology. While these methods can achieve relatively greater sensitivity compared to conventional univariate techniques, they still lack an established and accessible implementation. The aim of current work was to build an open-source R toolbox - "PredPsych" - that could make these methods readily available to all psychologists. PredPsych is a user-friendly, R toolbox based on machine-learning predictive algorithms. In this paper, we present the framework of PredPsych via the analysis of a recently published multiple-subject motion capture dataset. In addition, we discuss examples of possible research questions that can be addressed with the machine-learning algorithms implemented in PredPsych and cannot be easily addressed with univariate statistical analysis. We anticipate that PredPsych will be of use to researchers with limited programming experience not only in the field of psychology, but also in that of clinical neuroscience, enabling computational assessment of putative bio-behavioral markers for both prognosis and diagnosis.

Preschoolers out of adults: Discriminative learning with a cognitive load

This paper explores novel predictions from the spontaneous overtraining interpretation of human discrimination shift learning (Sirois & Shultz, 1998a). Results from six experiments where adults perform a discrimination shift task with or without a cognitive distractor are reported. In three experiments with a concurrent distractor task (Experiments 1A, 2A, and 3A), performance of adults is comparable to what would be expected from preschoolers performing only the learning task. These adults show no dimensional transfer from initial learning, unless new attributes are introduced in shift learning. On the same tasks without a cognitive load (Experiments 1B, 2B, and 3B), performance is typical of normal adults. The discussion focuses on the relative ability of competing theoretical models (i.e., levels of processing, attentional mediation, and perceptual differentiation) to account for these data.

Response bias induced in rats by response effects

Two experiments examined whether response choice in rats is affected by the presentation of response-produced stimuli. Rats were first trained to emit two different responses, with each response producing a unique auditory stimulus. Subsequently, the former response-produced stimuli were presented while the two response options were freely available. Presentation of a former response-produced stimulus caused the rats to choose more frequently the response option that had previously produced that specific stimulus over the other response option. However, although statistically significant, this response-biasing effect was numerically weak and was only apparent when the stimuli no longer had a general response-activating effect. Moreover, in the case of relatively short presentations of the stimuli, the response-biasing effect was only present if, during testing, the responses continued to produce the auditory stimuli according to the response-effect mapping used during training. These results were discussed in terms of possible underlying associations and were contrasted with previous results from analogous human studies on action control by response-produced stimuli.

Experiential simulations of negated text information

We investigated the question of whether comprehenders mentally simulate a described situation even when this situation is explicitly negated in the sentence. In two experiments, participants read negative sentences such as There was no eagle in the sky, and subsequently responded to pictures of mentioned entities in the context of a recognition task. Participants’ responses following negative sentences were faster when the depicted entity matched rather than mismatched the negated situation. These results suggest that comprehenders simulate the negated situation when processing a negated sentence. The results thereby provide further support for the experiential-simulations view of language comprehension.

Manipulating inattentional blindness within and across sensory modalities

People often fail to consciously perceive visual events that are outside the focus of attention, a phenomenon referred to as inattentional blindness or IB (i.e., Mack & Rock, 1998). Here, we investigated IB for words within and across sensory modalities (visually and auditorily) in order to assess whether dividing attention across different senses has the same consequences as dividing attention within an individual sensory modality. Participants were asked to monitor a rapid stream of pictures or sounds presented concurrently with task-irrelevant words (spoken or written). A word recognition test was used to measure the processing for unattended words compared to word recognition levels after explicitly monitoring the word stream. We were able to produce high levels of IB for visually and auditorily presented words under unimodal conditions (Experiment 1) as well as under crossmodal conditions (Experiment 2). A further manipulation revealed, however, that IB is less prevalent when attention is divided across modalities than within the same modality (Experiment 3). These findings are explained in terms of the attentional load hypothesis and suggest that, contrary to some claims, attention resources are to a certain extent shared across sensory modalities.

The Search for Significance: A Few Peculiarities in the Distribution of P Values in Experimental Psychology Literature

In this project I investigate the use and possible misuse of p values in papers published in five (high-ranked) journals in experimental psychology. I use a data set of over 135’000 p values from more than five thousand papers. I inspect (1) the way in which the p values are reported and (2) their distribution. The main findings are following: first, it appears that some authors choose the mode of reporting their results in an arbitrary way. Moreover, they often end up doing it in such a way that makes their findings seem more statistically significant than they really are (which is well known to improve the chances for publication). Specifically, they frequently report p values “just above” significance thresholds directly, whereas other values are reported by means of inequalities (e.g. “p<.1”), they round the p values down more eagerly than up and appear to choose between the significance thresholds and between one- and two-sided tests only after seeing the data. Further, about 9.2% of reported p values are inconsistent with their underlying statistics (e.g. F or t) and it appears that there are “too many” “just significant” values. One interpretation of this is that researchers tend to choose the model or include/discard observations to bring the p value to the right side of the threshold.

Familiarity with the experimenter influences the performance of Common ravens (Corvus corax) and Carrion crows (Corvus corone corone) in cognitive tasks

•

We compared the results of corvids in experiments with familiar/unfamiliar humans.

•

We investigated behavioural reactions towards familiar and unfamiliar humans.

•

Corvids performed significantly better in experiments with familiar humans.

•

Corvids did not show more neophobia towards unfamiliar humans.

•

Hence, familiarity positively affected the experimental performance of corvids.

When humans and animals interact with one another over an extended time span they familiarise and may develop a relationship, which can exert an influence on both partners. For example, the behaviour of an animal in experiments may be affected by its relationship to the human experimenter. However, few studies have systematically examined the impact of human–animal relationships on experimental results. In the present study we investigated if familiarity with a human experimenter influences the performance of Common ravens (Corvus corax) and Carrion crows (Corvus corone corone) in interactive tasks. Birds were tested in two interactive cognitive tasks (exchange, object choice) by several experimenters representing different levels of familiarity (long and short-term). Our findings show that the birds participated more often in both tasks and were more successful in the exchange task when working with long-term experimenters than when working with short-term experimenters. Behavioural observations indicate that anxiety did not inhibit experimental performance but that the birds’ motivation to work differed between the two kinds of experimenters, familiar and less familiar. We conclude that human–animal relationships (i.e. familiarity) may affect the experimental performance of corvids in interactive cognitive tasks.

Has psychology "found its true path"? Methods, objectivity, and cries of "crisis" in early twentieth-century French psychology

This article explores how French psychologists understood the state of their field during the first quarter of the twentieth century, and whether they thought it was in crisis. The article begins with the Russian-born psychologist Nicolas Kostyleff and his announcement in 1911 that experimental psychology was facing a crisis. After briefly situating Kostyleff, the article examines his analysis of the troubles facing experimental psychology and his proposed solution, as well as the rather muted response his diagnosis received from the French psychological community. The optimism about the field evident in many of the accounts surveying French psychology during the early twentieth century notwithstanding, a few others did join Kostyleff in declaring that all was not well with experimental psychology. Together their pronouncements suggest that under the surface, important unresolved issues faced the French psychological community. Two are singled out: What was the proper methodology for psychology as a positive science? And what kinds of practices could claim to be objective, and in what sense? The article concludes by examining what these anxieties reveal about the type of science that French psychologists hoped to pursue.

The role of tone sensation and musical stimuli in early experimental psychology

In this article, the role of music in early experimental psychology is examined. Initially, the research of Wilhelm Wundt is considered, as tone sensation and musical elements appear as dominant factors in much of his work. It is hypothesized that this approach was motivated by an understanding of psychology that dates back to Christian Wolff 's focus on sensation in his empirical psychology of 1732. Wolff, however, had built his systematization of psychology on Gottfried Wilhelm von Leibniz, who combined perception with mathematics,and referred to music as the area in which sensation is united with numerical exactitude. Immanuel Kant refused to accept empirical psychology as a science, whereas Johann Friedrich Herbart reintroduced the scientific basis of empirical psychology by, among other things, referring to music.

Little and often? Maintaining continued performance in an automated T-maze for mice

Operant and maze tasks in mice are limited by the small number of trials possible in a session before mice lose motivation. We hypothesized that by manipulating reward size and session length, motivation, and hence performance, would be maintained in an automated T-maze. We predicted that larger rewards and shorter sessions would improve acquisition; and smaller rewards and shorter sessions would maintain higher and less variable performance. Eighteen C57BL/6J mice (9 per sex) acquired (criterion 8/10 correct) and performed a spatial discrimination, with one of 3 reward sizes (.02, .04, or .08 g) and one of 3 session schedules (15, 30, or 45 min sessions). Each mouse had a total of 360 min of access to the maze per night, for two nights, and averaged 190 trials. Analysis used split-plot GLM with contrasts testing for linear effects. Acquisition of the discrimination was unaffected by reward size or session length/interval. After-criterion average performance improved as reward size decreased. After-criterion variability in performance was also affected. Variability increased as reward size increased. Session length/interval did not affect any outcome. We conclude that an automated maze, with suitable reward sizes, can sustain performance with low variability, at 5-10 times faster than traditional methods.

Eyelid conditioning to a target amplitude: adding how much to whether and when

Conceptual and practical advantages of pavlovian eyelid conditioning facilitate analysis of cerebellar computation and learning. Even so, eyelid conditioning procedures are unrealistic in an important way. The error signal to the olivocerebellar system does not decrease as learning adapts response amplitude or gain. This inherently limits the utility of eyelid conditioning for studies investigating how cerebellar learning mechanisms acquire and store an adaptive response amplitude. We report the development and characterization of a training procedure in which conditioned response amplitude is brought under experimental control with contingencies that more closely parallel natural conditions. In this procedure, the delivery of the unconditioned stimulus (US) is made contingent on conditioned response amplitude: the US is delivered for responses that fail to reach a specified target amplitude and is omitted for responses that meet or exceed the target. We find that rabbits trained with either a tone or with mossy fiber stimulation as the conditioned stimulus learn responses that approach target amplitudes ranging from 2 to 5 mm. Inactivating the interpositus nucleus with muscimol infusions abolished these conditioned responses, indicating that cerebellar involvement in eyelid conditioning is not tied explicitly to the use of pavlovian procedures. Together with previous studies, these data suggest that response amplitude is learned and encoded in the cerebellum during eyelid conditioning. As such, these results provide a foundation for systematic and controlled investigations of the cerebellar mechanisms that learn and encode the proper amplitude of adaptive movements.

Neural correlates of altered pain response in women with posttraumatic stress disorder from intimate partner violence

BACKGROUND

Intimate partner violence (IPV) is one of the most common causes of posttraumatic stress disorder (PTSD) in women. Women with IPV-related PTSD often experience comorbid chronic pain and pain-related disability. Despite the high comorbidity between PTSD and chronic pain, recent evidence suggests that male veterans with combat-related PTSD report decreased sensitivity to experimental pain. The aim of this study was to examine the neurobehavioral correlates of experimental pain in women with IPV-related PTSD.

METHODS

Functional magnetic resonance neuroimaging data were collected during an event-related experimental pain paradigm that was administered twice to 23 women with IPV-related PTSD and 15 age-, race- and education-comparable nontraumatized control women. Brief thermal heat stimuli were repeatedly applied to the left volar forearm, and subjects rated the perceived temperature intensity with a button-box.

RESULTS

Women with IPV-related PTSD relative to nontraumatized control women showed: 1) increased activation of right middle insula and right dorsolateral prefrontal cortex during initial painful stimulation, and 2) subsequent decrease in subjective intensity ratings with repeated exposure to pain, which was accompanied by attenuation of activation within right anterior insula that was associated with avoidance symptoms of PTSD.

CONCLUSIONS

These results suggest that women with IPV-related PTSD show dysregulated functional brain activity during pain processing, which might drive maladaptive coping mechanisms, such as avoidance and numbing.

Applying the permutation test to factorial designs

The permutation test follows directly from the procedure in a comparative experiment, does not depend on a known distribution for error, and is sometimes more sensitive to real effects than are the corresponding parametric tests. Despite its advantages, the permutation test is seldom (if ever) applied to factorial designs because of the computational load that they impose. We propose two methods to limit the computation load. We show, first, that orthogonal contrasts limit the computational load and, second, that when combined with Gill's (2007) algorithm, the factorial permutation test is both practical and efficient. For within-subjects designs, the factorial permutation test is equivalent to an ANOVA when the latter's assumptions have been met. For between-subjects designs, the factorial test is conservative. Code to execute the routines described in this article may be downloaded from http://brm.psychonomic-journals.org/content/supplemental.

A high-throughput method to measure NaCl and acid taste thresholds in mice

To develop a technique suitable for measuring NaCl taste thresholds in genetic studies, we conducted a series of experiments with outbred CD-1 mice using conditioned taste aversion (CTA) and two-bottle preference tests. In Experiment 1, we compared conditioning procedures involving either oral self-administration of LiCl or pairing NaCl intake with LiCl injections and found that thresholds were the lowest after LiCl self-administration. In Experiment 2, we compared different procedures (30-min and 48-h tests) for testing conditioned mice and found that the 48-h test is more sensitive. In Experiment 3, we examined the effects of varying strength of conditioned (NaCl or LiCl taste intensity) and unconditioned (LiCl toxicity) stimuli and concluded that 75-150 mM LiCl or its mixtures with NaCl are the optimal stimuli for conditioning by oral self-administration. In Experiment 4, we examined whether this technique is applicable for measuring taste thresholds for other taste stimuli. Results of these experiments show that conditioning by oral self-administration of LiCl solutions or its mixtures with other taste stimuli followed by 48-h two-bottle tests of concentration series of a conditioned stimulus is an efficient and sensitive method to measure taste thresholds. Thresholds measured with this technique were 2 mM for NaCl and 1 mM for citric acid. This approach is suitable for simultaneous testing of large numbers of animals, which is required for genetic studies. These data demonstrate that mice, like several other species, generalize CTA from LiCl to NaCl, suggesting that they perceive taste of NaCl and LiCl as qualitatively similar, and they also can generalize CTA of a binary mixture of taste stimuli to mixture components.

Measures of short-term memory: a historical review

Following Ebbinghaus (1885/1964), a number of procedures have been devised to measure short-term memory using immediate serial recall: digit span, Knox's (1913) cube imitation test and Corsi's (1972) blocks task. Understanding the cognitive processes involved in these tasks was obstructed initially by the lack of a coherent concept of short-term memory and later by the mistaken assumption that short-term and long-term memory reflected distinct processes as well as different kinds of experimental task. Despite its apparent conceptual simplicity, a variety of cognitive mechanisms are responsible for short-term memory, and contemporary theories of working memory have helped to clarify these. Contrary to the earliest writings on the subject, measures of short-term memory do not provide a simple measure of mental capacity, but they do provide a way of understanding some of the key mechanisms underlying human cognition.

EMuJoy: software for continuous measurement of perceived emotions in music

An adequate study of emotions in music and film should be based on the real-time measurement of self-reported data using a continuous-response method. The recording system discussed in this article reflects two important aspects of such research: First, for a better comparison of results, experimental and technical standards for continuous measurement should be taken into account, and second, the recording system should be open to the inclusion of multimodal stimuli. In light of these two considerations, our article addresses four basic principles of the continuous measurement of emotions: (1) the dimensionality of the emotion space, (2) data acquisition (e.g., the synchronization of media and the self-reported data), (3) interface construction for emotional responses, and (4) the use of multiple stimulus modalities. Researcher-developed software (EMuJoy) is presented as a freeware solution for the continuous measurement of responses to different media, along with empirical data from the self-reports of 38 subjects listening to emotional music and viewing affective pictures.

A methodology for the capture and analysis of hybrid data: a case study of program debugging

This article describes a methodology for the capture and analysis of hybrid data. A case study in the field of reasoning with multiple representations--specifically, in computer programming--is presented to exemplify the use of the methodology. The hybrid data considered comprise computer interaction logs, audio recordings, and data about visual attention focus. The capture of the focus of visual attention data is performed with software. The software employed tracks the user's visual attention by blurring parts of the stimuli presented on the screen and allowing the participant to see only a small region of it at any one time. These hybrid data are analyzed via a methodology that combines qualitative and quantitative approaches. The article describes the software tool employed and the analytic methodology, and also discusses data capture issues and limitations of the approach.

Multilevel models for the experimental psychologist: foundations and illustrative examples

Although common in the educational and developmental areas, multilevel models are not often utilized in the analysis of data from experimental designs. This article illustrates how multilevel models can be useful with two examples from experimental designs with repeated measurements not involving time. One example demonstrates how to properly examine independent variables for experimental stimuli or individuals that are categorical, continuous, or semicontinuous in the presence of missing data. The second example demonstrates how response times and error rates can be modeled simultaneously within a multivariate model in order to examine speed-accuracy trade-offs at the experimental-condition and individual levels, as well as to examine differences in the magnitude of effects across outcomes. SPSS and SAS syntax for the examples are available electronically.

Forgetting due to retroactive interference: a fusion of Müller and Pilzecker's (1900) early insights into everyday forgetting and recent research on anterograde amnesia

Ebbinghaus' seminal work suggested that forgetting occurred as a function of time. However, it raised a number of fundamental theoretical issues that still have not been resolved in the literature. Müller and Pilzecker (1900) addressed some of these issues in a remarkable manner but their observations have been mostly ignored in recent years. Müller and Pilzecker (1900) showed that the materials and the task that intervene between presentation and recall may interfere with the to-be-remembered items, and they named this phenomenon "retroactive interference" (RI). They further asked whether there is a type of RI that is based only on distraction, and not on the similarity between the memoranda and the interfering stimuli. Their findings, and our follow up research in healthy volunteers and amnesiacs, confirm that forgetting can be induced by any subsequent mentally effortful interpolated task, irrespective of its content; the interpolated "interfering" material does not have to be similar to the to-be-remembered stimuli.

Development of the Real-Time Subjective Emotionality Assessment (RTSEA) system

A new Real-Time Subjective Emotionality Assessment (RTSEA) system was developed for this study. The system is composed of two parts: an emotionality input and evaluation parts. An experiment was conducted in order to investigate the effectiveness of the RTSEA system. The present study compared Galvanic Skin Response (GSR) with the RTSEA by presenting 28 subjects with pictures that aroused either positive or negative emotion. Following the experiment, a subjective assessment using a questionnaire was given to the same subjects. According to the correlation coefficients, changes of the RTSEA had strong correlations with the changes of the GSR. Also, the questionnaire results showed marked similarity to the average responses of the RTSEA. In conclusion, the most remarkable characteristic of the present system is that it not only assesses the average emotionality when stimuli are presented, but also shows the trend of change in emotionality over time.

The analysis of behavior: what's in it for us?

When we publish behavioral research, we are not allowed to communicate the thrill, the poetry, or the exhilaration that are outcomes of the discovery process. Yet, these are among our most potent reinforcers. Explicit recognition of the emotional accompaniments to research could help attract students into the experimental analysis of behavior.

Failures to find suppression of episodic memories in the think/no-think paradigm

Anderson and Green (2001) had subjects learn paired associates and then selectively suppress responses to some of them. They reported a decrease in final cued recall for responses that subjectshad been instructed not to think of and explained their data as resulting from cognitive suppression, a laboratory analog of repression. We report three experiments designed to replicate the suppression/repression results. After subjects learned a series of A-B word pairs (e.g., ordsea-roach), they were then asked to respond to some items and not to think of other items when shown their cues 1, 8, or 16times. During a final recall test, they were cued with either asame (direct)probe (ordeal-__) or a n independent(indirect) probe (insect-r__) . None of our experiments showed reliable suppression effects with either the same or independent-probe tests. Suppression is apparently not a robust experimental phenomenon in the think/no-think paradigm.

Validating the Restricted Focus Viewer: A study using eye-movement tracking

Investigation of cognitive processes and visual attention during problem-solving tasks is an important part of understanding human reasoning. Eyetracking technology has proven to have many benefits in revealing visual attention patterns. However, the high price of accurate eyetrackers and the difficulties associated with using them represent major obstacles to their wider application. Therefore, previous studies have sought to find alternatives to eyetracking. The Restricted Focus Viewer (RFV) brings a small part of an otherwise blurred display to the focus of visual attention: A user controls what part of the screen is in focus by using a computer mouse and explicitly selecting the area to be shown in focus. Recently, some studies have employed the RFV to investigate cognitive behavior of users, and some researchers have even enhanced the tool to study usability. We replicated a previous RFV-based study while also recording gaze data. We compared the attention allocation in time and space as reported by the RFV and an eyetracker. Further, we investigated the effects of RFV's display blurring on the visual attention allocation of 18 novice and expert programmers. Our results indicate that the data obtained from the two tools differ. Also, the RFV-blurring interferes with the strategies utilized by experts, and has an effect on fixation duration. However, task performance was preserved.

Relations among functional systems in behavior analysis

This paper proposes that an organism's integrated repertoire of operant behavior has the status of a biological system, similar to other biological systems, like the nervous, cardiovascular, or immune systems. Evidence from a number of sources indicates that the distinctions between biological and behavioral events is often misleading, engendering counterproductive explanatory controversy. A good deal of what is viewed as biological (often thought to be inaccessible or hypothetical) can become publicly measurable variables using currently available and developing technologies. Moreover, such endogenous variables can serve as establishing operations, discriminative stimuli, conjoint mediating events, and maintaining consequences within a functional analysis of behavior and need not lead to reductionistic explanation. I suggest that explanatory misunderstandings often arise from conflating different levels of analysis and that behavior analysis can extend its reach by identifying variables operating within a functional analysis that also serve functions in other biological systems.

DEWEX: A system for designing and conducting Web-based experiments

DEWEX is a server-based environment for developing Web-based experiments. It provides many features for creating and running complex experimental designs on a local server. It is freeware and allows forboth using default features, for which only text input is necessary, and easy configurations that can be set up by the experimenter. The tool also provides log files on the local server that can be interpreted and analyzed very easily. As an illustration of how DEWEX can be used, a recent study is presented that demonstrates the system's most important features. This study investigated learning from multiple hypertext sources and shows the influences of task, source of information, and hypertext presentation format on the construction of mental representations of a hypertext about a historical event.

HMMTree: A computer program for latent-class hierarchical multinomial processing tree models

Latent-class hierarchical multinomial models are an important extension of the widely used family of multinomial processing tree models, in that they allow for testing the parameter homogeneity assumption and provide a framework for modeling parameter heterogeneity. In this article, the computer program HMMTree is introduced as a means of implementing latent-class hierarchical multinomial processing tree models. HMMTree computes parameter estimates, confidence intervals, and goodness-of-fit statistics for such models, as well as the Fisher information, expected category means and variances, and posterior probabilities for class membership. A brief guide to using the program is provided.

Experimental comparison of dyspnea and pain

Dyspnea and pain are similarly unpleasant, alarming physical sensations, but studies examining both sensations in combination are lacking. In the present study, dyspnea was induced in 7 healthy volunteers by breathing through inspiratory resistive loads and the effects were compared with those of a heat pain stimulus. End-tidal partial pressures of carbon dioxide (PET(CO2)), inspiratory time (Ti), breathing frequency (f), experienced unpleasantness, and intensity were measured. No difference was observed between dyspnea and pain in experienced intensity and unpleasantness (p > .05). During dyspneic stimulation, slightly higher Ti was found than for pain (p < .08). PET(CO2) showed slight increases during the dyspneic versus the baseline and painful conditions (deltaPET(CO2) = 1.5 and 1.3 mmHg, respectively; p < .01 andp < .05). This study shows that the effects of dyspnea and heat pain can be compared within one experiment; both stimuli can be presented with similar intensity and unpleasantness, which is a prerequisite for comparing responses to them. The changes in PET(CO2) between our conditions were minimal, allowing an application of the present design to future fMRI studies.

[Mexidol effects in extreme conditions (experiments with animals)]

In extreme conditions like a new situation, bright light, open space, immobilization, height (the open field and lifted cruciform labyrinth test) and a conflict between an unavoidable action and fear of painful mexidol at the doses of 50 and 100 mg/kg of a body weight eliminates anxiety and fear in rats, recovers adequate reactions and the orientative-trying behavior, and lessens aggressiveness. Mexidol extends life span of mice in acute hypoxic conditions. Mexidol is highly competitive with diazepam as an anti-stress agent and excels it as an anti-hypoxic agent; in contrast to diazepam, mexidol does not cause sedation and myorelaxation. Based on these findings, mexidol can be prescribed to humans to maintain efficiency in all kinds of extreme situations.

Cumulative intertrial inhibition in repeated visual search

In the present study the author examined visual search when the items remain visible across trials but the location of the target varies. Reaction times for inefficient search cumulatively increased with increasing numbers of repeated search trials, suggesting that inhibition for distractors carried over successive trials. This intertrial inhibition held across at least 16 items and when the search items moved randomly; however, it disappeared when the search items were removed from the display in an intertrial interval. In contrast, improvements to search when a target appeared at the same location on successive trials were weakened in a dynamic display, and this effect was resistant to the removal of search items. This dissociation implies that intertrial inhibition is based on a different mechanism than intertrial facilitation. The potential mechanisms for these effects are discussed.

Parameterizing the attentional blink effect

The attentional blink effect (AB) is used to examine the limits of attention in dual-task paradigms. However, since the effect is nonlinear, it is sometimes difficult to characterize the results. Furthermore, it is difficult to assess the significance of the effect between groups because the results are highly variable both within and across subjects. In this paper, we propose a method to quantify four characteristics of the AB curve: the minimum performance, the amplitude between the minimum and the asymptotic performance, the amount of Lag-1 sparing, and the width of the effect. The method, based on curve fitting, allows easier comparisons of the results across experiments, can test only one characteristic at a time, and yields more powerful statistical tests.

Behavioral determinants of drug action. The contributions of Peter B. Dews

Peter B. Dews played a significant role in shaping the distinctive characteristics and defining the underlying principles of the discipline of behavioral pharmacology. His early and sophisticated use of schedules of reinforcement in the 1950s, incorporated from research in the experimental analysis of behavior and integrated into the discipline of pharmacology, provided tremendous insight, inspiration, and impetus to the newly emerging field of behavioral pharmacology. The experimental findings generated by Dews' research, blending the sophisticated use of behavior and pharmacological principles together with the elegant manner of their presentation and far-reaching implications, provided the force and momentum to establish and direct behavioral pharmacology for several decades. This article attempts to capture some of Dews' research that integrated and inspired the blending of sophisticated behavioral work with that of pharmacology.

The role of perceptual integration in the recognition of assimilated word forms

We investigated how spoken words are recognized when they have been altered by phonological assimilation. Previous research has shown that there is a process of perceptual compensation for phonological assimilations. Three recently formulated proposals regarding the mechanisms for compensation for assimilation make different predictions with regard to the level at which compensation is supposed to occur as well as regarding the role of specific language experience. In the present study, Hungarian words and nonwords, in which a viable and an unviable liquid assimilation was applied, were presented to Hungarian and Dutch listeners in an identification task and a discrimination task. Results indicate that viably changed forms are difficult to distinguish from canonical forms independent of experience with the assimilation rule applied in the utterances. This reveals that auditory processing contributes to perceptual compensation for assimilation, while language experience has only a minor role to play when identification is required.

Experiments on the Fehrer-Raab effect and the 'Weather Station Model' of visual backward masking

The Fehrer-Raab effect (simple reaction time is unaffected by metacontrast masking of the test stimulus) seems to imply that a stimulus can trigger a voluntary reaction without reaching a conscious representation. However, it is also possible that the mask triggers the reaction, and that the masked test stimulus causes a focussing of attention from which processing of the mask profits, thus reaching conscious representation earlier. This is predicted by the Weather Station Model of visual masking. Three experiments tested this explanation. Experiment 1 showed that the masked test stimulus caused a temporal shift of the mask. Experiment 2 showed that the reaction in the Fehrer-Raab effect was not exclusively triggered by a conscious representation of the test stimulus: the mask was involved in evoking the reaction. Experiment 3 again revealed a temporal shift of the mask. However, the shift was only about half as large as the Fehrer-Raab effect. The psychometric functions suggested that the observers used two different cues for their temporal order judgments. The results cast doubts on whether judged temporal order yields a direct estimate of the time of conscious perception. Some methodological alternatives are discussed.

Is the meta-analysis of correlation coefficients accurate when population correlations vary?

One conceptualization of meta-analysis is that studies within the meta-analysis are sampled from populations with mean effect sizes that vary (random-effects models). The consequences of not applying such models and the comparison of different methods have been hotly debated. A Monte Carlo study compared the efficacy of Hedges and Vevea's random-effects methods of meta-analysis with Hunter and Schmidt's, over a wide range of conditions, as the variability in population correlations increases. (a) The Hunter-Schmidt method produced estimates of the average correlation with the least error, although estimates from both methods were very accurate; (b) confidence intervals from Hunter and Schmidt's method were always slightly too narrow but became more accurate than those from Hedges and Vevea's method as the number of studies included in the meta-analysis, the size of the true correlation, and the variability of correlations increased; and (c) the study weights did not explain the differences between the methods.

Bayesian eggs and Bayesian omelettes: Reply to Stern (2005)

In this response to Stern's (2005) discussion of Klugkist, Laudy, and Hoijtink (2005), model inference based on posterior probabilities on the parameter space is discussed. Furthermore, the authors respond to Stern's example in which all possible orderings are included via a short discussion of exploratory versus theory-based modeling. Finally, the authors show that the Bayesian approach is flexible and can deal with many types of constraints. This is illustrated using a model with constraints on the differences between means.

The legacy of Adolf Meyer’s comparative approach: Worcester rats and the strange birth of the animal model

The breeding of albino rats had an enormous impact on experimental psychology in the twentieth century. Rats were, and for many questions still remain, the "standard animal" for laboratory research in neurology, psychology, and physiology. Albert Meyer was one of the figures most responsible for developing the albino rat as an experimental model. Despite Meyer's pioneering work with albino rats, his rat research has received only sparse attention. Little is known about the way in which the animal served Meyer's more famous psychiatric program. In this article, the author discusses the role that albino rats played in Meyer's animal research. He then turn to the contrast between the way in which Meyer viewed the animal's role in research and the way rats were later used as a laboratory "standard" to assure scientific generality. This comparison highlights the changes that occurred in comparative psychology in the twentieth century, and it further clarifies some of the concerns associated with the use of animal models today.

Measuring automatic retrieval: a comparison of implicit memory, process dissociation, and speeded response procedures

Using the stem completion task, we compared estimates of automatic retrieval from an implicit memory task, the process dissociation procedure, and the speeded response procedure. Two standard manipulations were employed. In Experiment 1, a depth of processing effect was found on automatic retrieval using the speeded response procedure although this effect was substantially reduced in Experiment 2 when lexical processing was required of all words. In Experiment 3, the speeded response procedure showed an advantage of full versus divided attention at study on automatic retrieval. An implicit condition showed parallel effects in each study, suggesting that implicit stem completion may normally provide a good estimate of automatic retrieval. Also, we replicated earlier findings from the process dissociation procedure, but estimates of automatic retrieval from this procedure were consistently lower than those from the speeded response procedure, except when conscious retrieval was relatively low. We discuss several factors that may contribute to the conflicting outcomes, including the evidence for theoretical assumptions and criterial task differences between implicit and explicit tests.

Is Self Special? A Critical Review of Evidence From Experimental Psychology and Cognitive Neuroscience

Varied research findings have been taken to support the claim that humans' representation of the self is "special," that is, that it emerges from systems that are physically and functionally distinct from those used for more general purpose cognitive processing. The authors evaluate this claim by reviewing the relevant literatures and addressing the criteria for considering a system special, the various operationalizations of self, and how the studies' findings relate to the conclusions drawn. The authors conclude that many of the claims for the special status of self-related processing are premature given the evidence and that the various self-related research programs do not seem to be illuminating a unitary, common system, despite individuals' subjective experience of a unified self.

Operationism in psychology: what the debate is about, what the debate should be about

I offer an analysis of operationism in psychology, which is rooted in an historical study of the investigative practices of two of its early proponents (S. S. Stevens and E. C. Tolman). According to this analysis, early psychological operationists emphasized the importance of experimental operations and called for scientists to specify what kinds of operations were to count as empirical indicators for the referents of their concepts. While such specifications were referred to as "definitions," I show that such definitions were not taken to constitute a priori knowledge or be analytically true. Rather, they served the pragmatic function of enabling scientists to do research on a purported phenomenon. I argue that historical and philosophical discussions of problems with operationism have conflated it, both conceptually and historically, with positivism, and I raise the question of what are the "real" issues behind the debate about operationism.

A Simple Effect Size Indicator for Two-Group Comparisons? A Comment on requivalent

R. Rosenthal and D. B. Rubin (2003) proposed an effect size, r equivalent, to be used when (a) only sample size and p values are known for a study, (b) there are no generally accepted effect size indicators, or (c) sample sizes are so small or the data so non-normal that the directly computed effect sizes would be more misleading than the simple effect size. The limitations of their proposal, however, are many, and much more serious than the authors suggested, and should be carefully considered before this effect size is applied, as well as in developing other effect sizes using similar methods.

Experimental Research on Just-World Theory: Problems, Developments, and Future Challenges

M. J. Lerner (1980) proposed that people need to believe in a just world; thus, evidence that the world is not just is threatening, and people have a number of strategies for reducing such threats. Early research on this idea, and on just-world theory more broadly, was reviewed in early publications (e.g., M. J. Lerner, 1980; M. J. Lerner & D. T. Miller, 1978). In the present article, focus is directed on the post-1980 experimental research on this theory. First, 2 conceptualizations of the term belief in a just world are described, the typical experimental paradigms are explained, and a general overview of the post-1980 experiments is provided. Second, problems with this literature are discussed, including the unsystematic nature of the research. Third, important developments that have occurred, despite the problems reviewed, are described. Finally, theoretical challenges that researchers should address if this area of inquiry is to advance in the future are discussed.

Patterns of cortisol reactivity to laboratory stress

Cortisol responses to a laboratory stress protocol were investigated in 82 male firefighters. Saliva samples were collected during an adaptation period beginning between 9 and 10 am, and then at the end of each of six 10-min trials (a mental arithmetic task, an inter-task recovery period, a speech task, and three recovery periods). Individual differences in the mean cortisol response to the stress tasks were characterized by variation in the direction of the response, as well as the size of the response. Neither pre-stress cortisol levels nor responses were correlated with cardiovascular and mood responses. Cortisol levels before stress task presentation were negatively correlated with recent stress severity. Larger mean cortisol responses were associated with lower reports of recent stress exposure, lower negative affect scores, and a coping style characterized less experience of anger, more control over anger expression, and a tendency to screen out threatening information in stressful situations. Thus, increased cortisol activity was associated with less recent stress exposure and a more adaptive behavioral style than for those whose cortisol levels fell or were largely unchanged in response to a laboratory stressor.

Spacing one's study: evidence for a metacognitive control strategy

This article investigated individual control of spacing strategies during study. Three predictions were outlined: The spacing hypothesis suggests that people choose to space their study to improve long-term learning via the spacing effect. The massing hypothesis suggests that people choose to mass their study because of illusions of confidence during study. The metacognitive hypothesis suggests that people control their spacing schedules as a function of their metacognitive judgments of specific to-be-learned items. To test these hypotheses, the authors asked participants to study and make judgments of learning for cue-target pairs. Then, participants were given three choices; they could study the pair again immediately (massed), study the pair again after the entire list had been presented (spaced), or choose not to restudy (done). Results supported a metacognitively controlled spacing strategy-people spaced items that were judged to be relatively easy but massed items that were judged as relatively difficult.

SPSS and SAS programs for addressing interdependence and basic levels-of-analysis issues in psychological data

Levels-of-analysis issues arise whenever individual-level data are collected from more than one person from the same dyad, family, classroom, work group, or other interaction unit. Interdependence in data from individuals in the same interaction units also violates the independence-of-observations assumption that underlies commonly used statistical tests. This article describes the data analysis challenges that are presented by these issues and presents SPSS and SAS programs for conducting appropriate analyses. The programs conduct the within-and-between-analyses described by Dansereau, Alutto, and Yammarino (1984) and the dyad-level analyses described by Gonzalez and Griffin (1999) and Griffin and Gonzalez (1995). Contrasts with general multilevel modeling procedures are then discussed.

Using logistic regression to estimate delay-discounting functions

The monetary choice questionnaire (MCQ) and similar computer tasks ask preference questions in order to ascertain indifference, the perceived equivalence of immediate versus larger delayed rewards. Indifference data are then fitted with a hyperbolic function, summarizing the decline in perceived value with delay time. We present a fitting method that estimates the hyperbolic parameter k directly from survey responses. Binary preferences are modeled as a function of time (X2) and a transformed reward ratio (X1), yielding logistic regression coefficients beta 2 and beta 1. The hyperbolic parameter emerges as k = beta 2/beta 1, where the logistic predicted p = .5 (the definition of indifference). The MCQ was administered to 1,073 adolescents and was scored using both standard and logistic methods. The means for In(k) were similar (standard, -4.53; logistic, -4.51), and the results were highly correlated (rho = .973). Simulated MCQ data showed that k was unbiased, except where beta 1 > or = -1, indicating a vague survey response. Jackknife standard errors provided excellent coverage.

Implementing communication between Windows PCs and test equipment using RS-232 and Borland C++ Builder

Modern experiments in the behavioral sciences frequently employ several items of electronic equipment such as computers, monitoring devices, stimulus presentation equipment, and response collection systems. In many cases it would be advantageous for these items to communicate directly with each other. Such communication may facilitate greater automation of experiments (i.e., reduced experimenter influences during the experiment), more precise experiment control (i.e., superior timing and synchronization capabilities of electronic devices), and greater accuracy of data collection (i.e., reduced ambiguity of participant responses). Many electronic experiment devices already provide external interfaces through which communication with other devices can be implemented. The most common is based on the RS-232 protocol, which is also found in all standard PCs. Therefore, Microsoft Windows based computers can be programmed to control experiments by communicating directly with electronic experiment devices. We show how to implement this RS-232 interconnection between devices and a Windows PC using currently available software tools.