Application of the ex-Gaussian function to the effect of the word blindness suggestion on Stroop task performance suggests no word blindness

Variability of Reaction Time as a Marker of Executive Function Impairments in Fibromyalgia

In addition to chronic widespread pain and depression and anxiety symptoms, patients with fibromyalgia frequently experience cognitive problems. This study investigated executive functions in fibromyalgia via a Go/No-Go task. To obtain comprehensive information about performance, traditional and ex-Gaussian parameters of reaction time (RT) variability were used, in addition to speed and accuracy indices. Ex-Gaussian parameters show an excellent fit to empirical RT distributions. Fifty-two female fibromyalgia patients and twenty-eight healthy controls participated. The task included 60 visual stimuli, which participants had to respond to (Go stimuli) or withhold the response to (No-Go stimuli). After 30 trials, the task rule changed, such that previous No-Go stimuli had to be responded to. Performance was indexed by the hit rate, false alarm rate, and mean (M) and intraindividual standard deviation (SD) of RT and the ex-Gaussian parameters mu, sigma, and tau. Mu and sigma indicate the M and SD of the Gaussian distribution; tau reflects the M and SD of the exponential function. Patients exhibited a lower hit rate, higher M RT, and higher tau than controls. Moreover, patients showed greater decrease of the hit rate after the change of task rule. In the entire sample, SD, sigma, and tau were inversely associated with the hit rate and positively associated with the false alarm rate. While the greater decline in hit rate after the change in task rule indicates deficient cognitive flexibility, the lack of any difference in false alarm rate suggests intact response inhibition. Higher M RT reflects reduced cognitive or motor speed. Increased tau in fibromyalgia indicates greater fluctuations in executive control and more frequent temporary lapses of attention. For the first time, this study demonstrated that indices of RT variability, in particular those derived from the ex-Gaussian function, may complement speed and accuracy parameters in the assessment of executive function impairments in fibromyalgia. Optimized assessment may facilitate the personalization of therapies aimed at improving the cognitive function of those with the disorder.

Strategies that reduce Stroop interference

A remarkable example of reducing Stroop interference is provided by the word blindness post-hypnotic suggestion (a suggestion to see words as meaningless during the Stroop task). This suggestion has been repeatedly demonstrated to halve Stroop interference when it is given to highly hypnotizable people. In order to explore how highly hypnotizable individuals manage to reduce Stroop interference when they respond to the word blindness suggestion, we tested four candidate strategies in two experiments outside of the hypnotic context. A strategy of looking away from the target words and a strategy of visual blurring demonstrated compelling evidence for substantially reducing Stroop interference in both experiments. However, the pattern of results produced by these strategies did not match those of the word blindness suggestion. Crucially, neither looking away nor visual blurring managed to speed up incongruent responses, suggesting that neither of these strategies is the likely underlying mechanism of the word blindness suggestion. Although the current results did not unravel the mystery of the word blindness suggestion, they showed that there are multiple voluntary ways through which participants can dramatically reduce Stroop interference.

Deployment dynamics of hypnotic anger modulation

To understand the role that attention plays in the deployment timeline of hypnotic anger modulation, we composed an Attentional Blink paradigm where the first and second targets were faces, expressing neutral or angry emotions. We then suppressed the salience of angry faces through a "hypnotic numbing" suggestion. We found that hypnotic suggestion only attenuated the emotional salience of the second target (T2). By implementing drift-diffusion decision modelling, we also found that hypnotic suggestion mainly affected decision thresholds. These findings suggest that hypnotic numbing resulted from belated changes in response strategy. Interestingly, a contrast against non-hypnotized participants revealed that the numbing suggestion had the instruction-like feature of incorporating emotional valence into the attentional task-set. Together, our results portray hypnotic anger modulation as a two-tiered process: first, hypnotic suggestion alters the attentional task-set; second, provided processing and response preparation are not interrupted, a hypnotizability-dependent response based on said altered task-set is produced through late cognitive control strategies.

Look into my eyes: Pupillometry reveals that a post-hypnotic suggestion for word blindness reduces Stroop interference by marshalling greater effortful control

The mechanisms underpinning the apparently remarkable levels of cognitive and behavioural control following hypnosis and hypnotic suggestion are poorly understood. Numerous independent studies have reported that Stroop interference can be reduced following a post-hypnotic suggestion that asks participants to perceive words as if made up of characters from a foreign language. This effect indicates that frontal executive functions can be more potent than is generally accepted and has been described as resulting from top-down control not normally voluntarily available. We employed eye tracking and pupillometry to investigate whether the effect results from voluntary visuo-attentional strategies (subtly looking away from the word to prevent optimal word processing), reduced response conflict but not overall conflict, Stroop effects being pushed from response selection to response execution (response durations) or increased proactive effortful control given enhanced contextual motivation (as indexed via pupil dilation). We replicated the reduction in Stroop interference following the suggestion despite removing any trials on which eye movements were not consistent with optimal word processing. Our data were inconclusive with regards to conflict type affected by the suggestion in the latency data, although preserved semantic conflict was evident in the pupil data. There was also no evidence of Stroop effects on response durations. However, we show that baseline-corrected pupil sizes were larger following the suggestion indicating the socio-cognitive context and experimental demands motivate participants to marshal greater effortful control.

Can unconscious intentions be more effective than conscious intentions? Test of the role of metacognition in hypnotic response

While several theories assume that responses to hypnotic suggestions can be implemented without executive intentions, the metacognitive class of theories postulate that the behaviors produced by hypnotic suggestions are intended and the accompanying feeling of involuntariness is only a consequence of strategically not being aware of the intention. Cold control theory asserts that the only difference between a hypnotic and non-hypnotic response is this metacognitive one, that is, whether or not one is aware of one's intention to perform the relevant act. To test the theory, we compared the performance of highly suggestible participants in reducing the Stroop interference effect in a post-hypnotic suggestion condition (word blindness: that words will appear as a meaningless foreign script) and in a volitional condition (asking the participants to imagine the words as a meaningless foreign script). We found that participants had equivalent expectations that the posthypnotic suggestion and the volitional request would help control the conflicting information. Further, participants felt they had more control over experiencing the words as meaningless with the request rather than the suggestion; and they experienced the request largely as imagination and the suggestion largely as perception. That is, we set up the interventions we required for the experiment to constitute a test of cold control theory. Both the suggestion and the request reduced Stroop interference. Crucially, there was Bayesian evidence that the reduction in Stroop interference was the same between the suggestion and the volitional request. That is, the results support the claim that responding hypnotically does not grant a person greater first order abilities than they have non-hypnotically, consistent with cold control theory.

How Do I Know What My Theory Predicts?

To get evidence for or against a theory relative to the null hypothesis, one needs to know what the theory predicts. The amount of evidence can then be quantified by a Bayes factor. Specifying the sizes of the effect one’s theory predicts may not come naturally, but I show some ways of thinking about the problem, some simple heuristics that are often useful when one has little relevant prior information. These heuristics include the room-to-move heuristic (for comparing mean differences), the ratio-of-scales heuristic (for regression slopes), the ratio-of-means heuristic (for regression slopes), the basic-effect heuristic (for analysis of variance effects), and the total-effect heuristic (for mediation analysis).

Detection and Attention for Auditory, Visual, and Audiovisual Speech in Children with Hearing Loss

OBJECTIVES

Efficient multisensory speech detection is critical for children who must quickly detect/encode a rapid stream of speech to participate in conversations and have access to the audiovisual cues that underpin speech and language development, yet multisensory speech detection remains understudied in children with hearing loss (CHL). This research assessed detection, along with vigilant/goal-directed attention, for multisensory versus unisensory speech in CHL versus children with normal hearing (CNH).

DESIGN

Participants were 60 CHL who used hearing aids and communicated successfully aurally/orally and 60 age-matched CNH. Simple response times determined how quickly children could detect a preidentified easy-to-hear stimulus (70 dB SPL, utterance "buh" presented in auditory only [A], visual only [V], or audiovisual [AV] modes). The V mode formed two facial conditions: static versus dynamic face. Faster detection for multisensory (AV) than unisensory (A or V) input indicates multisensory facilitation. We assessed mean responses and faster versus slower responses (defined by first versus third quartiles of response-time distributions), which were respectively conceptualized as: faster responses (first quartile) reflect efficient detection with efficient vigilant/goal-directed attention and slower responses (third quartile) reflect less efficient detection associated with attentional lapses. Finally, we studied associations between these results and personal characteristics of CHL.

RESULTS

Unisensory A versus V modes: Both groups showed better detection and attention for A than V input. The A input more readily captured children's attention and minimized attentional lapses, which supports A-bound processing even by CHL who were processing low fidelity A input. CNH and CHL did not differ in ability to detect A input at conversational speech level. Multisensory AV versus A modes: Both groups showed better detection and attention for AV than A input. The advantage for AV input was facial effect (both static and dynamic faces), a pattern suggesting that communication is a social interaction that is more than just words. Attention did not differ between groups; detection was faster in CHL than CNH for AV input, but not for A input. Associations between personal characteristics/degree of hearing loss of CHL and results: CHL with greatest deficits in detection of V input had poorest word recognition skills and CHL with greatest reduction of attentional lapses from AV input had poorest vocabulary skills. Both outcomes are consistent with the idea that CHL who are processing low fidelity A input depend disproportionately on V and AV input to learn to identify words and associate them with concepts. As CHL aged, attention to V input improved. Degree of HL did not influence results.

CONCLUSIONS

Understanding speech-a daily challenge for CHL-is a complex task that demands efficient detection of and attention to AV speech cues. Our results support the clinical importance of multisensory approaches to understand and advance spoken communication by CHL.

Response Time Distribution Analysis of Semantic and Response Interference in a Manual Response Stroop Task

Abstract. Previous analyses of response time distributions have shown that the Stroop effect is observed in the mode (μ) and standard deviation (σ) of the normal part of the distribution, as well as its tail (τ). Specifically, interference related to semantic and response processes has been suggested to specifically affect the mode and tail, respectively. However, only one study in the literature has directly manipulated semantic interference, and none manipulating response interference. The present research aims to address this gap by manipulating both semantic and response interference in a manual response Stroop task, and examining how these components of Stroop interference affect the response time distribution. Ex-Gaussian analysis showed both semantic and response conflict to only affect τ. Analyzing the distribution by rank-ordered response times (Vincentizing) showed converging results as the magnitude of both semantic and response conflict increased with slower response times. Additionally, response conflict appeared earlier on the distribution compared to semantic conflict. These findings further highlight the difficulty in attributing specific psychological processes to different parameters (i.e., μ, σ, and τ). The effect of different response modalities on the makeup of Stroop interference is also discussed.

Task conflict in the Stroop task: When Stroop interference decreases as Stroop facilitation increases in a low task conflict context

In the present study participants completed two blocks of the Stroop task, one in which the response-stimulus interval (RSI) was 3500 ms and one in which RSI was 200 ms. It was expected that, in line with previous research, the shorter RSI would induce a low Task Conflict context by increasing focus on the color identification goal in the Stroop task and lead to a novel finding of an increase in facilitation and simultaneous decrease in interference. Such a finding would be problematic for models of Stroop effects that predict these indices of performance should be affected in tandem. A crossover interaction is reported supporting these predictions. As predicted, the shorter RSI resulted in incongruent and congruent trial reaction times (RTs) decreasing relative to a static neutral baseline condition; hence interference decreased as facilitation increased. An explanatory model (expanding on the work of Goldfarb and Henik, 2007) is presented that: (1) Shows how under certain conditions the predictions from single mechanism models hold true (i.e., when Task conflict is held constant); (2) Shows how it is possible that interference can be affected by an experimental manipulation that leaves facilitation apparently untouched; and (3) Predicts that facilitation cannot be independently affected by an experimental manipulation.