The interaction between self-bias and reward: Evidence for common and distinct processes

The perceptual matching of shapes and labels can be affected by both self- and reward-biases when shapes are linked either to labels referring to particular individuals (you, friend, stranger) or to different reward values (£8, £2, £0). We investigated the relations between these biases by varying the reward value associated with particular shape–label pairs (circle–you, square–friend, triangle–stranger). Self shape–label pairs (circle–you) always received no reward, while friend shape–label pairs (square–friend) received high reward and stranger shape–label pairs low reward (triangle–stranger), or the reverse (friend—low reward; stranger—high reward). Despite receiving no reward, responses to self-related pairs were advantaged relative to those to low-reward stimuli and did not differ from those to high-reward items. There was also an advantage for responses to high-reward friend pairs relative to low-reward stranger stimuli, and for high-reward stranger stimuli compared to low-reward friends. Correlations across individuals were found across trial blocks for both the self-advantage and the high-reward advantage, but the self- and reward-advantages were uncorrelated. This suggests that the self- and reward-advantage effects have different origins. In addition, the magnitude of the self-advantage varied according to the rated personal distance between a participant and a stranger. For individuals manifesting a close personal distance to strangers, the self-advantage was smaller, and sensitivity to reward influenced the difference between the self- and high-reward conditions. For individuals manifesting a large personal distance to strangers, sensitivity to reward did not affect self-matching. We suggest that self-advantages on perceptual matching arise independent of reward for individuals with a large personal distance to strangers. On the other hand, in individuals with a weak self-bias, high reward and the self modulate a common subjective value system.     

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.     

Selective attention for masked and unmasked threatening words in anxiety: Effects of trait anxiety, state anxiety and awareness

We investigated the effects of awareness on selective attention for masked and unmasked verbal threat material using a computerised version of the emotional Stroop. Participants were assigned to the high trait anxious (HTA) and low trait anxious (LTA) groups on the basis of questionnaire scores, and state anxiety was manipulated within participants through the threat of electric shock. To investigate the effects of awareness on responses to threat, the mode of exposure was blocked such that half the participants received masked trials before the unmasked trials, whereas the other half received the reverse order. The results revealed that there was no difference between the HTA and LTA groups in responses to threat for those who received the masked trials before the unmasked trials. However, when unmasked trials were presented before the masked trials HTA individuals were significantly slower to respond to both masked and unmasked threat words compared to the LTA group, and these effects were not further modified by participants' state anxiety status. The results are discussed in terms of the automatic nature of threat processing in anxiety.     

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.     

Spatial attention-related modulation of the N170 by backward masked fearful faces

Facial expressions are a basic form of non-verbal communication that convey important social information to others. The relevancy of this information is highlighted by findings that backward masked facial expressions facilitate spatial attention. This attention effect appears to be mediated through a neural network consisting of the amygdala, anterior cingulate, and visual cortex. However, a direct investigation of the neural time course associated with orienting to such stimuli has yet to be performed. In the current investigation, a backward masked fearful face dot-probe task was performed while ERPs were recorded. Reaction time results suggest that spatial attention is captured by backward masked fearful faces and attention is focused at the location of the fear stimulus. Masked right visual field fearful faces enhanced the N170 amplitudes of contralateral occipito-temporal electrodes. The rapid contralateral N170 enhancement was positively correlated with participants’ behavioral index of spatial attention. Thus, backward masked fearful face-elicited spatial attention facilitates behavior and modulates the early stage of facial processing reflected by the N170.     

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.     

Repeating a strongly masked stimulus increases priming and awareness

Previous studies [Marcel, A. J. (1983). Conscious and unconscious perception: Experiments on visual masking and word recognition. Cognitive Psychology, 15(2), 197–237; Wentura, D., & Frings, C. (2005). Repeated masked category primes interfere with related exemplars: New evidence for negative semantic priming. Journal of Experimental Psychology: Learning, Memory, and Cognition, 31(1), 108–120] suggested that repeatedly presenting a masked stimulus improves priming without increasing perceptual awareness. However, neural theories of consciousness predict the opposite: Increasing bottom-up strength in such a paradigm should also result in increasing availability to awareness. Here, we tested this prediction by manipulating the number of repetitions of a strongly masked digit. Our results do not replicate the dissociation observed in previous studies and are instead suggestive that repeating an unconscious and attended masked stimulus enables the progressive emergence of perceptual awareness.     

Now you see it,now you don't: The context dependent nature of category-effects in visual object recognition

In two experiments, we test predictions regarding processing advantages/disadvantages for natural objects and artefacts in visual object recognition. Varying three important parameters—degree of perceptual differentiation, stimulus format, and stimulus exposure duration—we show how different category-effects can be provoked in normal subjects on the same task. We interpret the results in light of the Pre-semantic Account of Category Effects (PACE; Gerlach, 2009), and conclude that category-effects do not reflect absolute processing differences between categories. Rather, category-effects are products of common operations which are differentially affected by the structural similarity among objects (with natural objects being more structurally similar than artefacts). The potentially most important aspect of the present study is the demonstration that category-effects are very context dependent; an aspect which has been neglected in earlier literature on category-specificity. PACE provides a useful framework in this respect, as it specifies how category-effects are influenced by changes in task and stimulus characteristics.     

Recognizing disguised faces

Across three experiments, we evaluated the effects of “disguises” on observers’ face identification performance using naturalistic images in which individuals posed with a variety of wigs and eyeglasses. Experiment 1 tested recognition memory performance with and without disguises and showed that any changes in these facial attributes hindered performance, replicating previous findings. More interestingly, Experiment 1 revealed that a change in hairstyle or the removal of eyeglasses had more impact on performance than did the addition of eyeglasses. In Experiment 2, disguised and undisguised faces were presented upright or inverted to examine whether the performance decrements seen in Experiment 1 were attributable to disruption of processing strategies for faces. Despite showing an overall effect of disguise on performance, there was no interaction between inversion and disguise. This suggests that disguises are not directly affecting processing strategies, but instead disguises are likely encoded as part of the overall representation. Similarly, in Experiment 3, the composite face paradigm was used to examine whether the impact of disguises is attributable to disruption of holistic processing for faces. Again, we found an overall effect of disguise on performance, but here we also observed that the presence of disguises interacted with participants’ tendency to form holistic face representations.