The effect of statistical learning on internal stimulus representations: Predictable items are enhanced even when not predicted

Statistical learning is the automatic and unconscious learning of environmental regularities and is a basic mechanism of learning in a variety of human perceptual and cognitive domains. Previous studies have mainly focused on the associative mechanisms of statistical learning. However, an unexplored question is whether the internal representations of individual stimuli are altered as their associations are learned. Using a temporal statistical learning paradigm, we examine this question across three experiments and find clear evidence that the internal representations of individual stimuli are differentially altered according to their degree of temporal predictability. These findings complement previous accounts of statistical learning and reveal an enriched mechanism of human learning, such that learning to associate items also enhances the representations of certain items relative to others.     

Thought Suppression in Spider-Fearful and Nonfearful Individuals

The authors examined the suppression of spider-related thoughts in spiderfearful (n = 23) and nonfearful (n = 22) individuals. Participants were primed with vivid pictures of spiders and a story about spiders. Next, they were randomly assigned to 1 of 2 conditions: (a) suppression of thoughts associated with the previously presented spiderrelated stimuli or (b) free expression of any thoughts, including those related to the spider-related stimuli. All participants completed a subsequent free-expression exercise. Results indicated that spider-fearful individuals expressed thoughts about the spider-related stimuli for a longer length of time than did nonfearful individuals, particularly in the suppression condition. Participants in both groups demonstrated a rebound of thoughts associated with the spider-related stimuli following suppression. The authors propose that the priming of feared stimuli makes suppression of fear-related thoughts particularly difficult for fearful individuals, perhaps by activating a state of heightened arousal.     

Role of prior negative cognitions on the development of intrusive thoughts

This analogue study examined how individuals' prior negative cognitions influenced intrusion frequency, intrusion‐related distress and thought suppression. Participants at high (HR) and low risk (LR) for interpreting their intrusive thoughts in a negative manner viewed a graphic trauma film and their subsequent intrusion development was assessed. HR participants experienced a greater frequency of intrusions and intrusion‐related distress compared to LR participants. Trait thought suppression moderated the relationship between risk for the negative interpretation of intrusions and intrusion frequency. The findings suggest that pre‐existing negative cognitions are influential in the development of intrusions following exposure to an analogue trauma.     

Hemispheric specialization for emotional word processing is a function of SSRI responsiveness

Vulnerability to depression and non-response to Selective Serotonin Reuptake Inhibitors (SSRIs) are associated with specific neurophysiological characteristics including greater right hemisphere (RH) relative to left hemisphere (LH) activity. The present study investigated the relationship between hemispheric specialization and processing of emotional words using a divided visual field paradigm administered to never-depressed and previously-depressed individuals, who were subdivided into SSRI responders and non-responders. SSRI responders and never-depressed participants were similar in their left hemispheric lateralization for evaluating emotional words. In contrast, SSRI non-responders showed a relative shift towards RH processing of negative words, and a strong bias toward negative evaluation of words presented to the RH. The results are discussed within the context of a biological-cognitive model of vulnerability to depression.     

Refining the visual-cortical hypothesis in category learning

Participants produce steep typicality gradients and large prototype-enhancement effects in dot-distortion category tasks, showing that in these tasks to-be-categorized items are compared to a prototypical representation that is the central tendency of the participant’s exemplar experience. These prototype-abstraction processes have been ascribed to low-level mechanisms in primary visual cortex. Here we asked whether higher-level mechanisms in visual cortex can also sometimes support prototype abstraction. To do so, we compared dot-distortion performance when the stimuli were size constant (allowing some low-level repetition-familiarity to develop for similar shapes) or size variable (defeating repetition-familiarity effects). If prototype formation is only mediated by low-level mechanisms, stimulus-size variability should lessen prototype effects and flatten typicality gradients. Yet prototype effects and typicality gradients were the same under both conditions, whether participants learned the categories explicitly or implicitly and whether they received trial-by-trial reinforcement during transfer tests. These results broaden out the visual-cortical hypothesis because low-level visual areas, featuring retinotopic perceptual representations, would not support robust category learning or prototype-enhancement effects in an environment of pronounced variability in stimulus size. Therefore, higher-level cortical mechanisms evidently can also support prototype formation during categorization.     

Dreaming and personality: Wake-dream continuity,thought suppression,and the Big Five Inventory

Studies have found relationships between dream content and personality traits, but there are still many traits that have been underexplored or have had questionable conclusions drawn about them. Experimental work has found a ‘rebound’ effect in dreams when thoughts are suppressed prior to sleep, but the effect of trait thought suppression on dream content has not yet been researched. In the present study participants (N = 106) reported their Most Recent Dream, answered questions about the content of the dream, and completed questionnaires measuring trait thought suppression and the ‘Big Five’ personality traits. Of these, 83 were suitably recent for analyses. A significant positive correlation was found between trait thought suppression and participants’ ratings of dreaming of waking-life emotions, and high suppressors reported dreaming more of their waking-life emotions than low suppressors did. The results may lend support to the compensation theory of dreams, and/or the ironic process theory of mental control.     

Perceiving expressions of emotion: What evidence could bear on questions about perceptual experience of mental states?

What evidence could bear on questions about whether humans ever perceptually experience any of another’s mental states, and how might those questions be made precise enough to test experimentally? This paper focusses on emotions and their expression. It is proposed that research on perceptual experiences of physical properties provides one model for thinking about what evidence concerning expressions of emotion might reveal about perceptual experiences of others’ mental states. This proposal motivates consideration of the hypothesis that categorical perception of expressions of emotion occurs, can be facilitated by information about agents’ emotions, and gives rise to phenomenal expectations. It is argued that the truth of this hypothesis would support a modest version of the claim that humans sometimes perceptually experience some of another’s mental states. Much available evidence is consistent with, but insufficient to establish, the truth of the hypothesis. We are probably not yet in a position to know whether humans ever perceptually experience others’ mental states.     

Magnocellular facilitation of flanked-letter identification disappears with strong flanker interference

Previously, we obtained evidence to suggest that the magnocellular system may reduce interference from flankers during flanked-letter identification. To understand this phenomenon better, we combined the data of our previous experiments, which all used the same flanking letter, and focused on the different target letters that were used. The new analysis showed that after an initial increase, magnocellular facilitation decreased and ultimately disappeared, as the target–flanker combination's level of interference increased. The initial increase was partly while the later decrease was fully replicated in two new experiments that focused on two different target letters while manipulating flanker identity. The outcome of a third new experiment studying the type of interference reduced suggested that although crowding contributed to total interference, it was insensitive to magnocellular mediation. Our results may be understood to reflect the involvement of the magnocellular system in an attentional-selection mechanism that is silenced by surround suppression.     

Unnoticed intrusions: Dissociations of meta-consciousness in thought suppression

The current research investigates the interaction between thought suppression and individuals’ explicit awareness of their thoughts. Participants in three experiments attempted to suppress thoughts of a prior romantic relationship and their success at doing so was measured using a combination of self-catching and experience-sampling. In addition to thoughts that individuals spontaneously noticed, individuals were frequently caught engaging in thoughts of their previous partner at experience-sampling probes. Furthermore, probe-caught thoughts were: (i) associated with stronger decoupling of attention from the environment, (ii) more likely to occur under cognitive load, (iii) more frequent for individuals with a desire to reconcile, and (iv) associated with individual differences in the tendency to suppress thoughts. Together, these data suggest that individuals can lack meta-awareness that they have begun to think about a topic they are attempting to suppress, providing novel insight into the cognitive processes that are involved in attempting to control undesired mental states.     

A Preliminary Examination of Thought Suppression,Emotion Regulation,and Coping in a Trauma-Exposed Sample

Attempts to modulate negative emotional and cognitive symptoms of posttraumatic stress disorder (PTSD) may be related to psychopathology. Trauma-exposed undergraduates, 31 reporting severe PTSD symptoms (PTSD group) and 34 without PTSD symptoms (non-PTSD group), completed measures of PTSD, depression, anxiety, thought control, emotion regulation, and coping. The PTSD group had greater psychopathology and overall modulation strategy use than the non-PTSD group. Thought suppression, emotion suppression, and avoidant coping strategies were positively related to psychopathology, whereas emotion reappraisal and approach coping strategies were either not related or weakly negatively related. Hierarchical multiple regressions with psychopathologic variables as criteria and modulation strategies as predictors indicated significant models in all cases. Generally, thought suppression was the only significant independent predictor of psychopathology.