Evidence for perceptual learning with repeated stimulation after partial and total cortical blindness

Lesions of occipital cortex result in loss of sight in the corresponding regions of visual fields. The traditional view that, apart from some spontaneous recovery in the acute phase, field defects remain permanently and irreversibly blind, has been challenged. In patients with partial field loss, a range of residual visual abilities in the absence of conscious perception (blindsight) has been demonstrated (Weiskrantz, 1986). Recent findings (Sahraie et al., 2006, 2010) have also demonstrated increased visual sensitivity in the field defect following repeated stimulation. We aimed to extend these findings by systematically exploring whether repeated stimulation can also lead to increased visual sensitivity in two cases with total (bilateral) cortical blindness. In addition, for a case of partial blindness, we examined the extent of the recovery as a function of stimulated region of the visual field, over extended periods of visual training. Positive auditory feedback was provided during the training task for correct detection of a spatial grating pattern presented at specific retinotopic locations using a temporal two alternative forced-choice paradigm (Neuro-Eye Therapy). All three cases showed improved visual sensitivity with repeated stimulation. The findings indicate that perceptual learning can occur through systematic visual field stimulation even in cases of bilateral cortical blindness.     

The effect of eye size on discriminating faces: Can infants recognize facial uncanniness?

Infants' ability to recognize uncanny human faces increases during the first year of life. In turn, their ability to recognize faces of other species declines at almost the same period (perceptual narrowing). In the current study, we aimed to clarify the relationship between the perception of uncanniness of faces and perceptual narrowing in infants and adults. We used the “uncanny valley task,” in which the participants were required to discriminate the faces of humans and monkeys by different eye size. Results showed that 3‐ to 5‐month‐old infants could not discriminate either monkey or human faces by eye size, whereas 6‐ to 8‐month olds could. Adults showed higher discrimination performance for human than monkey faces and perceived the human faces with extremely large or small eyes as exceedingly eerie. Our results suggest that perception of uncanniness of faces is formed after perceptual narrowing.     

Vahid,Burge, and Perceptual Entitlement

Hamid Vahid criticizes Tyler Burge's account of perceptual entitlement. Vahid argues that Burge's account fails to satisfy a criterion of adequacy that any correct account of perceptual warrant must satisfy. According to Vahid, a correct account of perceptual warrant must allow for perceptual beliefs which are produced by a properly functioning perceptual system yet which lack warrant. The present article argues that Vahid's critique of Burge fails. It presents numerous examples of such beliefs that are consistent with Burge's account of perceptual entitlement.     

语义饱和现象及其认知机制

大部分人有过长时间注视一个字之后突然不认识这个字,或多次重复背诵一个词语后会发现这个词变得“陌生”的经历.早期的心理学家发现在字词持续注意过程中语义会丢失,他们将这种现象命名为语义饱和.经过100多年的研究,众多心理学家发展了多种语义评价的方法来测量语义饱和,并发现语义饱和可能发生在知觉表征、语义加工或者词语表征与语义的联结阶段.类似的现象在中文等语标文字加工中表现出一种特有的字形饱和.近年来,新的认知心理学实验范式和神经科学技术的发展将有可能使得语义饱和研究取得重要的突破.     

How to be Conservative: a Partial Defence of Epistemic Conservatism

Conservatism about perceptual justification tells us that we cannot have perceptual justification to believe p unless we also have justification to believe that perceptual experiences are reliable. There are many ways to maintain this thesis, ways that have not been sufficiently appreciated. Most of these ways lead to at least one of two problems: the first is an over-intellectualization problem, whereas the second concerns the satisfaction of the epistemic basing requirement on justified belief. I argue that there is at least one Conservative view that survives both difficulties, a view which has the further ability to undercut a crucial consideration that has supported Dogmatist views about perceptual justification. The final section explores a tension between Conservatism and the prospect of having a completely general account of propositional justification. Ironically, the problem is that Conservatives seem committed to making the acquisition of propositional justification too easy. My partial defence of Conservatism concludes by suggesting possible solutions to this problem.     

Sense and Sensibility Educated: A Note on Experience and (Minimal) Empiricism

Abstract

McDowell’s minimal empiricism holds that experience, understood as providing conceptually articulated contents, plays a role in the justification of our beliefs. We question this idea by contrasting the role of perceptual experience in moral and non-moral judgments and conclude that experience per se is irrelevant in the former case and should also be so in the latter one: only with the help of adequate beliefs experience can provide a connection with the world. We conclude with some remarks concerning the importance of experience.     

Target self-relevance speeds visual search responses but does not improve search efficiency

ABSTRACT

In a variety of contexts, arbitrarily associating one’s self with a stimulus improves performance relative to stimuli that are not self-associated, implying enhanced processing of self-associated stimuli (“self-relevance” effects). Self-relevance has been proposed to influence diverse aspects of cognition, including the perceptual prioritization of self-relevant stimuli (“self-prioritization” effects). We sought to elucidate the mechanisms of self-prioritization by using a visual search paradigm. In three experiments, subjects learned two stimulus-label combinations (SELF and OTHER), and then searched for one of those stimuli (cued by the label) on each trial, with a variable number of distractors present on each trial. We hypothesized that, if self-relevance enhances the perceptual salience of the stimuli pre-attentively, then the self-relevance of a target should result in improved search efficiency. In three experiments using conjunction-defined (Experiments 1–2) and feature-defined (Experiment 3) targets, we found that self-relevant targets were associated with overall faster responses than non-self-relevant targets (an intercept effect). However, the slopes of the search size by reaction time (RT) function were never significantly different between the self-relevant and non-self-relevant conditions, counter to the hypothesis that self-prioritization is pre-attentive. These results constitute novel evidence that self-relevance affects visual search performance, but they also cast doubt on the possibility that self-relevance enhances the perceptual salience of a target in a manner similar to physical manipulations. We propose that the self-relevance of a stimulus alters processing only after the self-relevant item has been attended.     

High perceptual load causes inattentional blindness and deafness in drivers

ABSTRACT

Perceptual load theory of attention predicts that the level of perceptual load in a primary task affects the processing of additional stimuli. Given the lack of ecologically valid evidence for the model, the current study assessed the effect of perceptual load on driver awareness during simulated driving tasks. The results showed that perceptual load dramatically affected driver awareness for visual and auditory stimuli, even those that were driving relevant and safety critical (e.g. pedestrians or the sound of a car horn). The results support load theory and suggest that perceptual load may be an important factor in driver safety.     

Dissociable behavioural outcomes of visual statistical learning

ABSTRACT

Statistical learning refers to the extraction of probabilistic relationships between stimuli and is increasingly used as a method to understand learning processes. However, numerous cognitive processes are sensitive to the statistical relationships between stimuli and any one measure of learning may conflate these processes; to date little research has focused on differentiating these processes. To understand how multiple processes underlie statistical learning, here we compared, within the same study, operational measures of learning from different tasks that may be differentially sensitive to these processes. In Experiment 1, participants were visually exposed to temporal regularities embedded in a stream of shapes. Their task was to periodically detect whether a shape, whose contrast was staircased to a threshold level, was present or absent. Afterwards, they completed a search task, where statistically predictable shapes were found more quickly. We used the search task to label shape pairs as “learned” or “non-learned”, and then used these labels to analyse the detection task. We found a dissociation between learning on the search task and the detection task where only non-learned pairs showed learning effects in the detection task. This finding was replicated in further experiments with recognition memory (Experiment 2) and associative learning tasks (Experiment 3). Taken together, these findings are consistent with the view that statistical learning may comprise a family of processes that can produce dissociable effects on different aspects of behaviour.     

Tyler Burge on disjunctivism (II)

In McDowell (2010), I responded to Burge's attack (2005) on disjunctivism. In Burge (2011) Burge rejects my response. He stands by his main claim that disjunctivism is incompatible with the science of perception, and in a supplementary spirit he argues against the detail of my attempt to defend disjunctivism. Here I explain how disjunctivism is compatible with the science, and I respond to some of Burge's supplementary arguments.