Ultrasound and sonochemistry enhance education outcomes: From fundamentals and applied research to entrepreneurial potential

With this manuscript we aim to initiate a discussion specific to educational actions around ultrasonics sonochemistry. The importance of these actions does not just derive from a mere pedagogical significance, but they can be an exceptional tool for illustrating various concepts in other disciplines, such as process intensification and microfluidics. Sonochemistry is currently a far-reaching discipline extending across different scales of applicability, from the fundamental physics of tiny bubbles and molecules, up to process plants. This review is part of a special issue in Ultrasonics Sonochemistry, where several scholars have shared their experiences and highlighted opportunities regarding ultrasound as an education tool. The main outcome of our work is that teaching and mentorship in sonochemistry are highly needed, with a balanced technical and scientific knowledge to foster skills and implement safe protocols. Applied research typically features the use of ultrasound as ancillary, to merely enhance a given process and often leading to poorly conceived experiments and misunderstanding of the actual effects. Thus, our scientific community must build a consistent culture and monitor reproducible practices to rigorously generate new knowledge on sonochemistry. These practices can be implemented in teaching sonochemistry in classrooms and research laboratories. We highlight ways to collectively provide a potentially better training for scientists, invigorating academic and industry-oriented careers. A salient benefit for education efforts is that sonochemistry-based projects can serve multidisciplinary training, potentially gathering students from different disciplines, such as physics, chemistry and bioengineering. Herein, we discuss challenges, opportunities, and future avenues to assist in designing courses and research programs based on sonochemistry. Additionally, we suggest simple experiments suitable for teaching basic physicochemical principles at the undergraduatelevel. We also provide arguments and recommendations oriented towards graduate and postdoctoral students, in academia or industry to be more entrepreneurial. We have identified that sonochemistry is consistently seen as a 'green' or sustainable tool, which particular appeal to process intensification approaches, including microfluidics and materials science. We conclude that a globally aligned pedagogical initiative and constantly updated educational tools will help to sustain a virtuous cycle in STEM and industrial applications of sonochemistry.

On what motivates us: a detailed review of intrinsic v. extrinsic motivation

Motivational processes underlie behaviors that enrich the human experience, and impairments in motivation are commonly observed in psychiatric illness. While motivated behavior is often examined with respect to extrinsic reinforcers, not all actions are driven by reactions to external stimuli; some are driven by 'intrinsic' motivation. Intrinsically motivated behaviors are computationally similar to extrinsically motivated behaviors, in that they strive to maximize reward value and minimize punishment. However, our understanding of the neurocognitive mechanisms that underlie intrinsically motivated behavior remains limited. Dysfunction in intrinsic motivation represents an important trans-diagnostic facet of psychiatric symptomology, but due to a lack of clear consensus, the contribution of intrinsic motivation to psychopathology remains poorly understood. This review aims to provide an overview of the conceptualization, measurement, and neurobiology of intrinsic motivation, providing a framework for understanding its potential contributions to psychopathology and its treatment. Distinctions between intrinsic and extrinsic motivation are discussed, including divergence in the types of associated rewards or outcomes that drive behavioral action and choice. A useful framework for understanding intrinsic motivation, and thus separating it from extrinsic motivation, is developed and suggestions for optimization of paradigms to measure intrinsic motivation are proposed.

SpeedyIBL: A comprehensive, precise, and fast implementation of instance-based learning theory

Instance-based learning theory (IBLT) is a comprehensive account of how humans make decisions from experience during dynamic tasks. Since it was first proposed almost two decades ago, multiple computational models have been constructed based on IBLT (i.e., IBL models). These models have been demonstrated to be very successful in explaining and predicting human decisions in multiple decision-making contexts. However, as IBLT has evolved, the initial description of the theory has become less precise, and it is unclear how its demonstration can be expanded to more complex, dynamic, and multi-agent environments. This paper presents an updated version of the current theoretical components of IBLT in a comprehensive and precise form. It also provides an advanced implementation of the full set of theoretical mechanisms, SpeedyIBL, to unlock the capabilities of IBLT to handle a diverse taxonomy of individual and multi-agent decision-making problems. SpeedyIBL addresses a practical computational issue in past implementations of IBL models, the curse of exponential growth, that emerges from memory-based tabular computations. When more observations accumulate over time, there is an exponential growth of the memory of instances that leads directly to an exponential slowdown of the computational time. Thus, SpeedyIBL leverages parallel computation with vectorization to speed up the execution time of IBL models. We evaluate the robustness of SpeedyIBL over an existing implementation of IBLT in decision games of increased complexity. The results not only demonstrate the applicability of IBLT through a wide range of decision-making tasks, but also highlight the improvement of SpeedyIBL over its prior implementation as the complexity of decision features the of agents increase. The library is open sourced for the use of the broad research community.

Validating and Refining Cognitive Process Models Using Probabilistic Graphical Models

We describe a new approach for developing and validating cognitive process models. In our methodology, graphical models (specifically, hidden Markov models) are developed both from human empirical data on a task and synthetic data traces generated by a cognitive process model of human behavior on the task. Differences between the two graphical models can then be used to drive model refinement. We show that iteratively using this methodology can unveil substantive and nuanced imperfections of cognitive process models that can then be addressed to increase their fidelity to empirical data.

The jumping to conclusions reasoning bias as a cognitive factor contributing to psychosis progression and persistence: findings from NEMESIS-2

BACKGROUND

Contemporary models of psychosis implicate the importance of affective dysregulation and cognitive factors (e.g. biases and schemas) in the development and maintenance of psychotic symptoms, but studies testing proposed mechanisms remain limited. This study, uniquely using a prospective design, investigated whether the jumping to conclusions (JTC) reasoning bias contributes to psychosis progression and persistence.

METHODS

Data were derived from the second Netherlands Mental Health Survey and Incidence Study (NEMESIS-2). The Composite International Diagnostic Interview and an add-on instrument were used to assess affective dysregulation (i.e. depression, anxiety and mania) and psychotic experiences (PEs), respectively. The beads task was used to assess JTC bias. Time series analyses were conducted using data from T1 and T2 (N = 8666), excluding individuals who reported high psychosis levels at T0.

RESULTS

Although the prospective design resulted in low statistical power, the findings suggest that, compared to those without symptoms, individuals with lifetime affective dysregulation were more likely to progress from low/moderate psychosis levels (state of 'aberrant salience', one or two PEs) at T1 to high psychosis levels ('frank psychosis', three or more PEs or psychosis-related help-seeking behaviour) at T2 if the JTC bias was present [adj. relative risk ratio (RRR): 3.8, 95% confidence interval (CI) 0.8-18.6, p = 0.101]. Similarly, the JTC bias contributed to the persistence of high psychosis levels (adj. RRR: 12.7, 95% CI 0.7-239.6, p = 0.091).

CONCLUSIONS

We found some evidence that the JTC bias may contribute to psychosis progression and persistence in individuals with affective dysregulation. However, well-powered prospective studies are needed to replicate these findings.

The Simon effect in a discrete sequence production task: Key-specific stimuli cannot be ignored due to attentional capture

Two experiments examined whether practicing discrete key pressing sequences eventually leads to a disregard of the key-specific stimuli, as suggested by sequence learning models, or whether these stimuli continue to be relied upon because the associated luminance increase attracts visuospatial attention. Participants practiced two sequences by reacting to two fixed series of seven letter stimuli, each displayed at a location that did or did not correspond with the required response location. Stimulus use was indicated by a Simon effect in that key presses were slowed when stimulus and key locations did not correspond. Experiment 1 demonstrated that letter stimuli continued to be used as the Simon effect occurred with each sequence element, and this remained quite stable across practice and did not differ for familiar and unfamiliar sequences. Experiment 2 showed that the Simon effect remained present even with meaningless stimuli that were often even harmful. These findings suggest that even in motor sequences that can be executed without element-specific stimuli attention attraction enforces stimulus use. The data further supported the assumptions that S-R translation and sequencing systems are racing to trigger individual responses, and that explicit sequence representations include spatial and verbal knowledge.

[Cognitive explanations of auditory verbal hallucinations in schizophrenia: An inventory of the scientific literature]

AIMS

Our article consists in both analysis and synthesis of contemporary cognitive models of auditory verbal hallucinations (AVHs) in schizophrenia. Our work is based on the analysis of the scientific literature including original articles, literature reviews as well as meta-analysis.

METHODOLOGY

In order to identify the most pertinent studies in the electronic search, the three following databases were systematically searched: PubMed, PsycINFO and MEDLINE. For both the analysis and synthesis we selected original articles, literature reviews as well as meta-analysis referring to any cognitive explanation of the auditory hallucinatory experience in schizophrenia. A cognitive model of auditory hallucinations refers to any incorporation of cognitive frameworks and explanations in one's conceptualization of the hallucinatory phenomenon in schizophrenia. We also focused our work on past conceptualization of auditory hallucinations in order to explain the development and the contribution of current cognitive models in the understanding of the onset and the maintaining of AVHs. After a brief review of clinical characteristics and historical conceptualization of auditory verbal hallucinations, contemporary explanations were presented in the area of schizophrenia. These explanations referred to researches into cognitive psychopathology including metacognitive as well as neuroimaging studies.

RESULTS

The examination of scientific literature highlighted the complexity of AVHs through multifactorial explanations here mostly explained by cognitive and metacognitive deficits. We synthesized former conceptualizations of AVHs, which were sustained on mechanistic or sensory explanations. Esquirol, Baillarger and Briere de Boismont were the first as conceiving AVHs as a perception disorder and introduced the idea that auditory hallucinations resulted from a failure to control one's memories/fantasies. Later, Broca and Wernicke discovered auditory areas in the human brain implicated in language comprehension and production. AVHs began to be conceptualized by the scientific world as being mechanistically brain-related. Sigmund Freud was among the first to study the meaning of AVHs, a domain still being investigated by todays cognitive sciences. More recently, neuroimaging studies allowed the validation of these sensory explanations in considering the onset of AVHs through the deficit of cortical and subcortical areas implicated in the process of languages (e.g. Broca and Wernicke areas) and emotions (e.g. limbic system, amygdala, hippocampus). At a more mechanistic level, contemporary cognitive models of AVHs explained AVHs as an intrusive verbal representation into the awareness which is non-inhibited (i.e. deficit in intentional inhibition) and also non-recognized as one's own experience (i.e. deficit in source monitoring, planning and metacognition), or even attributed to an external source (attribution bias). In terms of inhibitory control, inhibition is a basic cognitive mechanism defined as a collection of processes that allows the suppression of previously activated cognitive contents and the clearing of irrelevant actions or attention from consciousness. Intentional inhibition is effortful and occurs when an individual deliberately suppresses the activation of an item after deciding it is irrelevant. Theoretical support for the suggestion that an inhibitory failure is involved in AVHs in schizophrenia arises from studies that have shown that a failure in inhibition results in intrusive thoughts from long-term memory. Recent findings also found that individuals with AVHs in schizophrenia demonstrated an impaired source monitoring. In episodic memory research, a distinction was made between content (an event) and context (e.g. source or temporal characteristics of an event) information. The context of memories provides cues that allow an individual to differentiate one memory from other memories. AVHs are conceptualized as a failure to access the contextual cues that would allow voice-hearer to form an intact representation of events in memories. Regarding planning, AVHs refer to the intrusion of unwanted memories into the inner speech that are not recognized from one's own representation. Previous cognitive theories highlighted the important role played by metacognitive skills and belief (i.e. thinking about one's thinking) in the explanation of AVHs. Finally, the external attribution bias was extensively studied over the last three decades and refers to the tendency to attribute negative events (situational or cognitive) to an external source. In this framework, AVHs refer to intrusive thoughts externally attributed to a voice.

CONCLUSION

For more than one century, scientific discoveries in (bio)medical science have allowed the validation of former sensory and mechanistic explanations of AVHs. Nevertheless, many explanatory models account for the way AVHs are maintained (source monitoring, deficit in planning, externalizing bias), while they scarcely expose how they are triggered (intrusive thoughts, deficit in inhibition). The relation between AVHs and intrusive thoughts still remain unclear, and further studies are needed for the understanding of a potential causal relationship.

Parameter Inference for Computational Cognitive Models with Approximate Bayesian Computation

This paper addresses a common challenge with computational cognitive models: identifying parameter values that are both theoretically plausible and generate predictions that match well with empirical data. While computational models can offer deep explanations of cognition, they are computationally complex and often out of reach of traditional parameter fitting methods. Weak methodology may lead to premature rejection of valid models or to acceptance of models that might otherwise be falsified. Mathematically robust fitting methods are, therefore, essential to the progress of computational modeling in cognitive science. In this article, we investigate the capability and role of modern fitting methods—including Bayesian optimization and approximate Bayesian computation—and contrast them to some more commonly used methods: grid search and Nelder–Mead optimization. Our investigation consists of a reanalysis of the fitting of two previous computational models: an Adaptive Control of Thought—Rational model of skill acquisition and a computational rationality model of visual search. The results contrast the efficiency and informativeness of the methods. A key advantage of the Bayesian methods is the ability to estimate the uncertainty of fitted parameter values. We conclude that approximate Bayesian computation is (a) efficient, (b) informative, and (c) offers a path to reproducible results.

On the importance of avoiding shortcuts in applying cognitive models to hierarchical data

Psychological experiments often yield data that are hierarchically structured. A number of popular shortcut strategies in cognitive modeling do not properly accommodate this structure and can result in biased conclusions. To gauge the severity of these biases, we conducted a simulation study for a two-group experiment. We first considered a modeling strategy that ignores the hierarchical data structure. In line with theoretical results, our simulations showed that Bayesian and frequentist methods that rely on this strategy are biased towards the null hypothesis. Secondly, we considered a modeling strategy that takes a two-step approach by first obtaining participant-level estimates from a hierarchical cognitive model and subsequently using these estimates in a follow-up statistical test. Methods that rely on this strategy are biased towards the alternative hypothesis. Only hierarchical models of the multilevel data lead to correct conclusions. Our results are particularly relevant for the use of hierarchical Bayesian parameter estimates in cognitive modeling.

The evolution of cognitive models: From neuropsychology to neuroimaging and back

This paper provides a historical and future perspective on how neuropsychology and neuroimaging can be used to develop cognitive models of human brain functions. Section 1 focuses on the emergence of cognitive modelling from neuropsychology, why lesion location was considered to be unimportant and the challenges faced when mapping symptoms to impaired cognitive processes. Section 2 describes how established cognitive models based on behavioural data alone cannot explain the complex patterns of distributed brain activity that are observed in functional neuroimaging studies. This has led to proposals for new cognitive processes, new cognitive strategies and new functional ontologies for cognition. Section 3 considers how the integration of data from lesion, behavioural and functional neuroimaging studies of large cohorts of brain damaged patients can be used to determine whether inter-patient variability in behaviour is due to differences in the premorbid function of each brain region, lesion site or cognitive strategy. This combination of neuroimaging and neuropsychology is providing a deeper understanding of how cognitive functions can be lost and re-learnt after brain damage - an understanding that will transform our ability to generate and validate cognitive models that are both physiologically plausible and clinically useful.

Modeling the Covariance Structure of Complex Datasets Using Cognitive Models: An Application to Individual Differences and the Heritability of Cognitive Ability

Understanding individual differences in cognitive performance is an important part of understanding how variations in underlying cognitive processes can result in variations in task performance. However, the exploration of individual differences in the components of the decision process-such as cognitive processing speed, response caution, and motor execution speed-in previous research has been limited. Here, we assess the heritability of the components of the decision process, with heritability having been a common aspect of individual differences research within other areas of cognition. Importantly, a limitation of previous work on cognitive heritability is the underlying assumption that variability in response times solely reflects variability in the speed of cognitive processing. This assumption has been problematic in other domains, due to the confounding effects of caution and motor execution speed on observed response times. We extend a cognitive model of decision-making to account for relatedness structure in a twin study paradigm. This approach can separately quantify different contributions to the heritability of response time. Using data from the Human Connectome Project, we find strong evidence for the heritability of response caution, and more ambiguous evidence for the heritability of cognitive processing speed and motor execution speed. Our study suggests that the assumption made in previous studies-that the heritability of cognitive ability is based on cognitive processing speed-may be incorrect. More generally, our methodology provides a useful avenue for future research in complex data that aims to analyze cognitive traits across different sources of related data, whether the relation is between people, tasks, experimental phases, or methods of measurement.

Negative trust and depression among female sex workers in Western China: The mediating role of thwarted belongingness

Female sex workers are at high risk for depression in China but they are understudied and underserved. Based on cognitive models of depression, dysfunctional beliefs about oneself and others may act as vulnerability factors for depression. However, the association between negative trust and depression is still under debate. The present study aimed to test the hypothesis that negative trust positively relates to depression through thwarted belongingness among female sex workers. Four hundred and fifty-seven participants completed measures of negative trust, thwarted belongingness, and depression. Stepwise multiple linear regression analyses showed that both negative trust and thwarted belongingness significantly positively predicted depression, and thwarted belongingness was positively predicted by negative trust. The results from the mediation analysis suggest that thwarted belongingness might be an underlying mechanism linking negative trust and depression. Psychological interventions could focus on helping female sex workers form and strengthen meaningful social connectedness (the behavioral/observable indicators of the constructs of thwarted belongingness).

The impact of appraisals on intrusive memories

BACKGROUND AND OBJECTIVES

Intrusive memories are a core feature of posttraumatic stress disorder (PTSD). Cognitive models posit that PTSD symptoms are stimulated by maladaptive appraisals about symptoms. This study aimed to test the causal pathway of maladaptive appraisals about the meaning of intrusions on subsequent intrusive memories.

METHODS

Forty-five healthy participants were presented with a traumatic film, and were subsequently told either (a) intrusions are indicative of poor psychological functioning, (b) intrusions are not indicative of psychological functioning, or (c) no instructions. Participants subsequently completed a measure of cognitive performance to index potential interference by intrusions, as well as a scale of intrusive memories.

RESULTS

Participants who were told that intrusions are indicative of negative psychological state subsequently reported more intrusive memories than those who were told that intrusions have no particular significance.

LIMITATIONS

Inferences are reduced by lack of group differences in appraisals reported by participants. A stronger index of intrusions would have been achieved through diary keeping in the period after the experimental session.

CONCLUSIONS

This finding provides initial causal evidence that appraising intrusions as maladaptive may directly enhance the occurrence of intrusions following encoding of an aversive event, and in this sense is supportive of cognitive models of PTSD.

[Time perception and schizophrenia: Phenomenological and neuropsychological approach]

OBJECTIVES

Based on clinical, phenomenological and neurobiological observations, psychiatrists often report a deficit in time estimation in patients with schizophrenia. Cognitive models of time estimation in healthy subjects have been proposed and developed for approximately 30 years. The investigation of time perception is pertinent to the understanding of neurobiological and cognitive abnormalities in schizophrenia. Brain lesions and neuroimaging studies have shown that the critical brain structures engaged in time perception include the prefrontal and parietal lobes, thalamus, basal ganglia and cerebellum. These brain areas have been implicated in the physiopathology of schizophrenia in that there is impaired coordination of activity among these regions. Clinical and experimental date strongly suggest that patients with schizophrenia are less accurate in their ability to estimate time than healthy subjects. The specificity of these clinical and behavioral impairments is still in question. The aims of this article are to present an overview of the literature regarding time estimation and schizophrenia, to discuss specific issues related to how perceptual dysfunction in schizophrenia may lead to abnormalities in time perception, and to propose new perspectives towards an integrative approach between phenomenology and neuroscience.

METHODS

We present a review of the literature describing the current theory in the field of time perception, which is supported by a connectionist model, postulating that temporal judgment is based upon a pacemaker-counter device that depends mostly upon memory and attentional resources. The pacemaker emits pulses that are accumulated in a counter, and the number of pulses determines the perceived length of an interval. Patients with schizophrenia are known to display attentional and memory dysfunctions. Moreover, dopamine regulation mechanisms are involved in both the temporal perception and schizophrenia.

DISCUSSION

It is still unclear if temporal impairments in schizophrenia are related to a specific disturbance in central temporal processes or are due to certain cognitive problems, such as attentional and memory dysfunctions, or biological abnormalities. While psychopathological and phenomenological work strongly suggests that time perception disturbance may be the key or core symptom in schizophrenia, neuroscience studies have failed to do the same. The question of specificity of temporal perception impairments in schizophrenia remains contested. Neuroscience studies suggest that time symptoms in patients with schizophrenia are only secondary to thought disorders and primary cognitive impairments. This debate refers to the etiologic/organic versus psychogenesis/psychological dichotomy and may be over-taken.

CONCLUSION

Clinical evidence associated with psychopathological, biological and cognitive theories strongly suggests that patients with schizophrenia have a deficit in time perception. Discrimination and reproduction of durations have been found to be constantly impaired and disorganized. There is still much work to be done to identify the exact sources of variability in temporal judgments in schizophrenia, and the study of developmental course of time perception could be an interesting route. Regardless of the role of temporal deficits in the pathogenesis of schizophrenia (as a general cognitive disorder or a core role), clinical and phenomenological data encourage us to conduct further studies, especially in the field of developmental psychology.

A functional synergistic model to explain postural control during precise visual tasks

In everyday life, individuals sometimes have to perform precise, or challenging, visual tasks in upright standing. Upright, one problem to perform precise saccades and fixations is that the body oscillates continuously in a mainly unpredictable way. Current cognitive models assume that the central nervous system should divide its attention to perform these 'dual tasks' because of limited attentional resources (keeping balance and performing the precise visual task). The problem with the concept of duality is that individuals (need to) succeed in precise visual tasks upright and should not be more unstable and inefficient - because of a division of attention - in these tasks. In our opinion, the central nervous system should work adaptively in a way that enables success in these tasks. Hence, instead of assuming 'duality' in cognitive processes, we suggest that i) a 'synergy' - or unification - between visual and postural processes may be required to succeed in precise visual tasks. Success in precise visual tasks upright would also require ii) the synergy to be based on two feedforward processes with the visual process being the leader; iii) individuals to reduce their postural sway to facilitate successful synergies; iiii) additional cognitive resources to link visual and postural processes. We discuss some literature findings consistent with these assumptions and summarize a recent validation of the synergistic model. In summary, both models of duality and synergy could be complementary and the present manuscript shows how they could be included in a higher-order, two directional, cognitive model of postural control.

Active vision task and postural control in healthy, young adults: Synergy and probably not duality

In upright stance, individuals sway continuously and the sway pattern in dual tasks (e.g., a cognitive task performed in upright stance) differs significantly from that observed during the control quiet stance task. The cognitive approach has generated models (limited attentional resources, U-shaped nonlinear interaction) to explain such patterns based on competitive sharing of attentional resources. The objective of the current manuscript was to review these cognitive models in the specific context of visual tasks involving gaze shifts toward precise targets (here called active vision tasks). The selection excluded the effects of early and late stages of life or disease, external perturbations, active vision tasks requiring head and body motions and the combination of two tasks performed together (e.g., a visual task in addition to a computation in one's head). The selection included studies performed by healthy, young adults with control and active - difficult - vision tasks. Over 174 studies found in Pubmed and Mendeley databases, nine were selected. In these studies, young adults exhibited significantly lower amplitude of body displacement (center of pressure and/or body marker) under active vision tasks than under the control task. Furthermore, the more difficult the active vision tasks were, the better the postural control was. This underscores that postural control during active vision tasks may rely on synergistic relations between the postural and visual systems rather than on competitive or dual relations. In contrast, in the control task, there would not be any synergistic or competitive relations.

Of matchers and maximizers: How competition shapes choice under risk and uncertainty

In a world of limited resources, scarcity and rivalry are central challenges for decision makers-animals foraging for food, corporations seeking maximal profits, and athletes training to win, all strive against others competing for the same goals. In this article, we establish the role of competitive pressures for the facilitation of optimal decision making in simple sequential binary choice tasks. In two experiments, competition was introduced with a computerized opponent whose choice behavior reinforced one of two strategies: If the opponent probabilistically imitated participant choices, probability matching was optimal; if the opponent was indifferent, probability maximizing was optimal. We observed accurate asymptotic strategy use in both conditions irrespective of the provision of outcome probabilities, suggesting that participants were sensitive to the differences in opponent behavior. An analysis of reinforcement learning models established that computational conceptualizations of opponent behavior are critical to account for the observed divergence in strategy adoption. Our results provide a novel appraisal of probability matching and show how this individually 'irrational' choice phenomenon can be socially adaptive under competition.

Quantum cognition: key issues and discussion

Quantum cognition is an emerging field that uses mathematical principles of quantum theory to help formalize and understand cognitive systems and processes. The topic on the potential of using quantum theory to build models of cognition (Volume 5, issue 4) introduces and synthesizes its new development through an introduction and six core articles. The current issue presents 14 commentaries on the core articles. Five key issues surface, some of which are interestingly controversial and debatable as expected for a new emerging field.

Discovering the sequential structure of thought

Multi-voxel pattern recognition techniques combined with Hidden Markov models can be used to discover the mental states that people go through in performing a task. The combined method identifies both the mental states and how their durations vary with experimental conditions. We apply this method to a task where participants solve novel mathematical problems. We identify four states in the solution of these problems: Encoding, Planning, Solving, and Respond. The method allows us to interpret what participants are doing on individual problem-solving trials. The duration of the planning state varies on a trial-to-trial basis with novelty of the problem. The duration of solution stage similarly varies with the amount of computation needed to produce a solution once a plan is devised. The response stage similarly varies with the complexity of the answer produced. In addition, we identified a number of effects that ran counter to a prior model of the task. Thus, we were able to decompose the overall problem-solving time into estimates of its components and in way that serves to guide theory.

Mechanisms of change in cognitive behaviour therapy for panic disorder: the role of panic self-efficacy and catastrophic misinterpretations

The efficacy of cognitive behavioural therapy (CBT) for panic disorder with or without agoraphobia (PD) is well-established; however, little is known about the underlying change processes of clinical improvement during therapy. According to cognitive theories, CBT for PD primarily works by changing catastrophic misinterpretations of bodily symptoms and panic attacks. However, panic self-efficacy, i.e. the perceived ability to cope with panic attacks, has also been suggested as an important change mechanism in CBT for PD. The aim of the study was to investigate if change in catastrophic misinterpretations and panic self-efficacy mediated change in the level of anxiety during the course of thirteen sessions of group CBT for PD. Forty-five participants completed weekly self-report measures of the possible cognitive mediators and the level of anxiety throughout therapy. The results indicated that within-person change in panic self-efficacy in one session, but not in catastrophic misinterpretations, predicted within-person level of anxiety symptoms the following week. However, in a reversed analysis, prior change in level of anxiety symptoms also predicted change in panic self-efficacy the following session. These results support panic self-efficacy as a mediator of change in CBT for PD, although a reciprocal causal relationship between panic self-efficacy and level of anxiety seems to be implied.

A generalized model for predicting postcompletion errors

A postcompletion error is a type of procedural error that occurs after the main goal of a task has been accomplished. There is a strong theoretical foundation accounting for postcompletion errors (Altmann & Trafton, 2002; Byrne & Bovair, 1997). This theoretical foundation has been leveraged to develop a logistic regression model of postcompletion errors based on reaction time and eye movement measures (Ratwani, McCurry, & Trafton, 2008). This study further develops and extends this predictive model by (a) validating the model and the general set of predictors on a new task to test the robustness of the model, and (b) determining which specific theoretical components are most important to postcompletion error prediction.