Tracking the first two seconds: three stages of visual information processing?

We compared visual priming and comparison tasks to assess information processing of a stimulus during the first 2 s after its onset. In both tasks, a 13-ms prime was followed at varying SOAs by a 40-ms probe. In the priming task, observers identified the probe as rapidly and accurately as possible; in the comparison task, observers determined as rapidly and accurately as possible whether or not the probe and prime were identical. Priming effects attained a maximum at an SOA of 133 ms and then declined monotonically to zero by 700 ms, indicating reliance on relatively brief visuosensory (iconic) memory. In contrast, the comparison effects yielded a multiphasic function, showing a maximum at 0 ms followed by a minimum at 133 ms, followed in turn by a maximum at 240 ms and another minimum at 720 ms, and finally a third maximum at 1,200 ms before declining thereafter. The results indicate three stages of prime processing that we take to correspond to iconic visible persistence, iconic informational persistence, and visual working memory, with the first two used in the priming task and all three in the comparison task. These stages are related to stages presumed to underlie stimulus processing in other tasks, such as those giving rise to the attentional blink.     

Holistic processing of shape cues in face identification: Evidence from face inversion,composite faces,and acquired prosopagnosia

According to a classical functional architecture of face processing (Bruce & Young, 1986), sex processing on faces is a parallel function to individual face recognition. One consequence of the model is thus that sex categorization on faces is not influenced by face familiarity. However, the behavioural and neuro-psychological evidences supporting this dissociation are yet equivocal. To test the independence between sex processing on faces and familiar face recognition, familiar (learned) faces were morphed with new faces, generating facial continua of visual similarity to familiar faces. First, a pilot experiment shown that subjects familiarized with one extreme of the face continuum roughly perceive one half of the continuum (60 to 100% of visual similarity to familiar faces) as made of familiar faces and the other part as unfamiliar. In the experiment proper, subjects were familiarized with faces and tested in a sex decision task made on faces at the different steps of the continua. Subjects were significantly quicker at telling the sex of faces perceived as familiar (60-100%), and the effect was not observed in a control (untrained) group. These results indicate that familiar face representations are activated before sex categorization is completed, and can facilitate this processing. The nature of the interaction between sex categorization on faces and familiar face recognition is discussed.     

A behavioural experiment in virtual reality to verify the role of action function in space coding

Neurophysiological data indicate that the reachable peripersonal space and the unreachable extrapersonal space are represented in segregated parietofrontal circuits and that when the unreachable space becomes reachable because of tool use, it is automatically coded by the network selective for peripersonal space. Here we directly tested the role of action's consequences in space coding. Thirty-eight participants bisected lines at either a reachable distance (60 cm) or unreachable distance (120 cm) using either a laser pointer or laser cutter. The laser cutter but not the laser pointer had an action consequence; the line broke into two pieces. The results showed that distance moderated the effect of action. At an unreachable distance, the mean bisection point was closer to the centre when participants used the laser cutter compared to when they used the laser pointer. There were no differences at a reachable distance (60 cm). This result suggests that the space in which the individual may determine a physical consequence is categorized as peripersonal space, independently from its actual distance from the individual's body.     

An independent component analysis of fMRI data of grapheme-colour synaesthesia

The independent component analysis (ICA) method was applied to fMRI data from two synaesthetes and their matched controls while they performed the coloured-word Stroop task and the single-letter (synaesthetic) Stroop task. ICA identified an 'attention' network, a 'perceptual' network as well as a 'conflict monitoring' network. Increased activity was observed in right V4 during the single-letter Stroop task for synaesthetes only. The finding confirms that the same neural substrate that is known to support the experience of physical colours also supports the experience of synaesthetic colours.     

Perceiving action identity: how pianists recognize their own performances

Can skilled performers, such as artists or athletes, recognize the products of their own actions? We recorded 12 pianists playing 12 mostly unfamiliar musical excerpts, half of them on a silent keyboard. Several months later, we played these performances back and asked the pianists to use a 5-point scale to rate whether they thought they were the person playing each excerpt (1 = no, 5 = yes). They gave their own performances significantly higher ratings than any other pianist's performances. In two later follow-up tests, we presented edited performances from which differences in tempo, overall dynamic (i.e., intensity) level, and dynamic nuances had been removed. The pianists' ratings did not change significantly, which suggests that the remaining information (expressive timing and articulation) was sufficient for self-recognition. Absence of sound during recording had no significant effect. These results are best explained by the hypothesis that an observer's action system is most strongly activated during perception of self-produced actions.     

Revisiting Snodgrass and Vanderwart's object pictorial set: the role of surface detail in basic-level object recognition

Theories of object recognition differ to the extent that they consider object representations as being mediated only by the shape of the object, or shape and surface details, if surface details are part of the representation. In particular, it has been suggested that color information may be helpful at recognizing objects only in very special cases, but not during basic-level object recognition in good viewing conditions. In this study, we collected normative data (naming agreement, familiarity, complexity, and imagery judgments) for Snodgrass and Vanderwart's object database of 260 black-and-white line drawings, and then compared the data to exactly the same shapes but with added gray-level texture and surface details (set 2), and color (set 3). Naming latencies were also recorded. Whereas the addition of texture and shading without color only slightly improved naming agreement scores for the objects, the addition of color information unambiguously improved naming accuracy and speeded correct response times. As shown in previous studies, the advantage provided by color was larger for objects with a diagnostic color, and structurally similar shapes, such as fruits and vegetables, but was also observed for man-made objects with and without a single diagnostic color. These observations show that basic-level 'everyday' object recognition in normal conditions is facilitated by the presence of color information, and support a 'shape + surface' model of object recognition, for which color is an integral part of the object representation. In addition, the new stimuli (sets 2 and 3) and the corresponding normative data provide valuable materials for a wide range of experimental and clinical studies of object recognition.     

Newborns' face recognition is based on spatial frequencies below 0.5 cycles per degree

A critical question in Cognitive Science concerns how knowledge of specific domains emerges during development. Here we examined how limitations of the visual system during the first days of life may shape subsequent development of face processing abilities. By manipulating the bands of spatial frequencies of face images, we investigated what is the nature of the visual information that newborn infants rely on to perform face recognition. Newborns were able to extract from a face the visual information lying from 0 to 1 cpd (Experiment 1), but only a narrower 0-0.5 cpd spatial frequency range was successful to accomplish face recognition (Experiment 2). These results provide the first empirical support of a low spatial frequency advantage in individual face recognition at birth and suggest that early in life low-level, non-specific perceptual constraints affect the development of the face processing system.     

Cortical Acetylcholine, Reality Distortion, Schizophrenia, and Lewy Body Dementia: Too Much or Too Little Cortical Acetylcholine?

Aberrations in cortical cholinergic transmission have been hypothesized to mediate the development and manifestation of psychotic cognition. Based primarily on hypotheses about mesolimbic dopaminergic hyperactivity in schizophrenia, the actions of antipsychotic drugs, the trans-synaptic regulation of the excitability of basal forebrain corticopetal cholinergic neurons, and the role of cortical cholinergic inputs in attentional functions, we hypothesized that persistent disinhibition of cortical cholinergic inputs mediates the fundamental cognitive dysfunctions which form the basis for the development of positive symptoms in schizophrenia. In contrast to this hypothesis, Perry and Perry (1995), based on evidence from hallucinating patients with Lewy Body Dementia (LBD), concluded that the extensivelossof cortical acetylcholine allows irrelevant information to enter “conscious awareness” and thus hallucinations to emerge. The discussion of these contrasting hypotheses highlights the need for more dynamic and precise theories describing the cognitive variables and neuronal processes which contribute to the development and manifestation of psychotic cognition. While the hypothesis that a disinhibited cholinergic system mediates the evolution of psychotic symptoms corresponds more convincingly with current theories about the cognitive functions of cortical cholinergic inputs, both hypotheses stress the critical role of cortical acetylcholine in the highest levels of cognitive functioning.     

Objective age-of-acquisition (AoA) norms for a set of 230 object names in French: Relationships with psycholinguistic variables,the English data from Morrison et al. (1997), and naming latencies

Picture naming speed is strongly influenced by the age of acquisition (AoA) of words. Most studies of AoA have relied on adults' AoA ratings. However, objective AoA has been found to be a stronger determinant of picture naming latencies. Whereas objective AoA norms for words have been collected for some language communities, no objective AoA measures for words were previously available in French. The study provides objective AoA norms for a set of 230 object names following the procedures used by Morrison, Chappell, and Ellis (1997) to collect objective AoA measures in English. The relationships between objective AoA measures, rated AoA, other variables used in psycholinguistic experiments (name agreement, image agreement, conceptual familiarity, etc.), the English data collected by Morrison et al., and naming latencies are analysed and discussed. In addition, reanalyses of data on picture naming latencies (Bonin, Chalard, Méot, & Fayol, 2002) with the use of objective AoA norms are provided. Stepwise multiple analyses show that objective AoA is a stronger determinant of (spoken and written) naming latencies than rated AoA, whereas objective word frequency is not a reliable independent determinant and does not interact reliably with AoA in any of the analyses.     

Action blindness in response to gradual changes

The goal of this study is to characterize observers’ abilities to detect gradual changes and to explore putative dissociations between conscious experience of change and behavioral adaptation to a changing stimulus. We developed a new experimental paradigm in which, on each trial, participants were shown a dot pattern on the screen. Next, the pattern disappeared and participants had to reproduce it. In some conditions, the target pattern was incrementally rotated over successive trials and participants were either informed or not of this change. We analyzed both awareness of the changes and the dynamics of behavioral adaptation, in a way that makes it possible to assess both variability and accuracy as they change over time. Results indicate a dissociation between change awareness and behavioral adaptation to the changes, and support the notion that unconscious representations of visual stimuli are more precise and detailed than previously suggested. We discuss the implications of these results for theories of change detection.