Visual pattern recognition in the cerebral hemispheres : the role of spatial filtering

The differences between the left and right cerebral hemispheres in terms of visual pattern recognition were examined in the context of the spatial filtering model of visual perception. On the basis of a wide range of evidence, it was hypothesized that the right hemisphere is superior in the processing of low spatial frequency and/or high contrast information, and that this superiority may underlie its predominant role in "gestalt" perception. The left hemisphere, on the other hand, was hypothesized to be more highly involved in an analysis of high frequency and/or low contrast information contained in the visual environment. The spatial filtering capabilities of the two hemispheres were assessed by presenting square-wave gratings to the left and right visual fields, which project almost exclusively to the primary visual cortical areas of the contralateral hemispheres. Twenty-four right-handed adult male subjects were required to discriminate two different orientations of each of six gratings varying in fundamental spatial frequency and level of contrast

Re-examination of Oostenbroek et al. (2016): evidence for neonatal imitation of tongue protrusion

The meaning, mechanism, and function of imitation in early infancy have been actively discussed since Meltzoff and Moore's (1977) report of facial and manual imitation by human neonates. Oostenbroek et al. (2016) claim to challenge the existence of early imitation and to counter all interpretations so far offered. Such claims, if true, would have implications for theories of social-cognitive development. Here we identify 11 flaws in Oostenbroek et al.'s experimental design that biased the results toward null effects. We requested and obtained the authors’ raw data. Contrary to the authors’ conclusions, new analyses reveal significant tongue-protrusion imitation at all four ages tested (1, 3, 6, and 9 weeks old). We explain how the authors missed this pattern and offer five recommendations for designing future experiments. Infant imitation raises fundamental issues about action representation, social learning, and brain–behavior relations. The debate about the origins and development of imitation reflects its importance to theories of developmental science

Development of gaze aversion: qualitiative changes over the early school years

Looking away from an interlocutors’ face during demanding cognitive activity can help adults and children answer challenging mental arithmetic and verbal-reasoning questions (Glenberg, Schroeder, & Robertson, 1998; Phelps, Doherty-Sneddon & Warnock, in press). Whilst such ‘gaze aversion’ (GA) is used far less by 5-year old school children, its use increases dramatically during the first years of primary education, reaching adult levels by 8-years of age (Doherty-Sneddon, Bruce, Bonner, Longbotham, & Doyle, 2002). The current study investigates whether developmental changes also occur in a qualitative aspect of GA - the direction of movement involved in GA shifts. Video data from 18 5-year-olds and 19 8-year-olds answering verbal and arithmetic questions were analysed for direction of GA. We found very different profiles of direction of GA across the two ages: whilst the 5-year-olds used predominantly rapid multi-directional ‘flicking’ movements and some sustained left lateral movements, the 8-year-olds used predominantly sustained rightward movements. It is concluded that, as well as quantitative increases in the use of GA across these age groups, there are concomitant qualitative changes in the nature of GA shifts. A model of human attention in face-to-face interaction is discussed as are implications for the assessment of children’s learning and development

Bisecting the mental number line in near and far space

Much evidence suggests that common posterior parietal mechanisms underlie the orientation of attention in physical space and along the mental number line. For example, the small leftward bias (pseudoneglect) found in paper-and-pencil line bisection is also found when participants "bisect" number pairs, estimating (without calculating) the number midway between two others. For bisection of physical lines, pseudoneglect has been found to shift rightward as lines are moved from near space (immediately surrounding the body) to far space. We investigated whether the presentation of stimuli in near or far space also modulated spatial attention for the mental number line. Participants bisected physical lines or number pairs presented at four distances (60, 120, 180, 240 cm). Clear rightward shifts in bias were observed for both tasks. Furthermore, the rate at which this shift occurred in the two tasks, as measured by least squares regression slopes, was significantly correlated across participants, suggesting that the transition from near to far distances induced a common modulation of lateral attention in physical and numerical space. These results demonstrate a tight coupling between number and physical space, and show that even such prototypically abstract concepts as number are modulated by our on-line interactions with the world

The effect of stopping before turning on the direct observational measure of whole body turning bias

Turning bias, the preferential tendency to turn toward a given direction has been reported in both rodents and human participants. The observational gait method of determining turning bias in humans requires a stop prior to turning. This study removed the stop and hypothesised that turning bias would remain the same between stop and non-stop conditions if bias was solely under the control of neurochemical asymmetries. The results showed that statistically turning bias remained the same (to the left) regardless of method used but there was no agreement between the methods thus rejecting the hypothesis. It is likely that when not stopping biomechanical factors related to gait when turning influence the direction of turn rather than solely neurochemical asymmetries

Influence of hand position on the near-effect in 3D attention

Voluntary reorienting of attention in real depth situations is characterized by an attentional bias to locations near the viewer once attention is deployed to a spatially cued object in depth. Previously this effect (initially referred to as the ‘near-effect’) was attributed to access of a 3D viewer-centred spatial representation for guiding attention in 3D space. The aim of this study was to investigate whether the near-bias could have been associated with the position of the response-hand, always near the viewer in previous studies investigating endogenous attentional shifts in real depth. In Experiment 1, the response-hand was placed at either the near or far target depth in a depth cueing task. Placing the response-hand at the far target depth abolished the near-effect, but failed to bias spatial attention to the far location. Experiment 2 showed that the response-hand effect was not modulated by the presence of an additional passive hand, whereas Experiment 3 confirmed that attentional prioritization of the passive hand was not masked by the influence of the responding hand on spatial attention in Experiment 2. The pattern of results is most consistent with the idea that response preparation can modulate spatial attention within a 3D viewer-centred spatial representation

Reaching within a dynamic virtual environment

This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Facilitating Stable Representations: Serial Dependence in Vision

We tested whether the intervening time between multiple glances influences the independence of the resulting visual percepts. Observers estimated how many dots were present in brief displays that repeated one, two, three, four, or a random number of trials later. Estimates made farther apart in time were more independent, and thus carried more information about the stimulus when combined. In addition, estimates from different visual field locations were more independent than estimates from the same location. Our results reveal a retinotopic serial dependence in visual numerosity estimates, which may be a mechanism for maintaining the continuity of visual perception in a noisy environment

Perceiving What Is Reachable Depends on Motor Representations: Evidence from a Transcranial Magnetic Stimulation Study

Background: Visually determining what is reachable in peripersonal space requires information about the egocentric location of objects but also information about the possibilities of action with the body, which are context dependent. The aim of the present study was to test the role of motor representations in the visual perception of peripersonal space. Methodology: Seven healthy participants underwent a TMS study while performing a right-left decision (control) task or perceptually judging whether a visual target was reachable or not with their right hand. An actual grasping movement task was also included. Single pulse TMS was delivered 80 % of the trials on the left motor and premotor cortex and on a control site (the temporo-occipital area), at 90 % of the resting motor threshold and at different SOA conditions (50ms, 100ms, 200ms or 300ms). Principal Findings: Results showed a facilitation effect of the TMS on reaction times in all tasks, whatever the site stimulated and until 200ms after stimulus presentation. However, the facilitation effect was on average 34ms lower when stimulating the motor cortex in the perceptual judgement task, especially for stimuli located at the boundary of peripersonal space. Conclusion: This study provides the first evidence that brain motor area participate in the visual determination of what is reachable. We discuss how motor representations may feed the perceptual system with information about possibl

Sharing Space: The Presence of Other Bodies Extends the Space Judged as Near

Background: As social animals we share the space with other people. It is known that perceived extension of the peripersonal space (the reaching space) is affected by the implicit representation of our own and other's action potentialities. Our issue concerns whether the co-presence of a body in the scene influences our extrapersonal space (beyond reaching distance) categorization. Methodology/Principal Findings: We investigated, through 3D virtual scenes of a realistic environment, whether egocentric spatial categorization can be influenced by the presence of another human body (Exp. 1) and whether the effect is due to her action potentialities or simply to her human-like morphology (Exp. 2). Subjects were asked to judge the location ("Near" or "Far") of a target object located at different distances from their egocentric perspective. In Exp. 1, the judgment was given either in presence of a virtual avatar (Self-with-Other), or a non-corporeal object (Self-with-Object) or nothing (Self). In Exp. 2, the Self condition was replaced by a Self-with-Dummy condition, in which an inanimate body (a wooden dummy) was present. Mean Judgment Transition Thresholds (JTTs) were calculated for each subject in each experimental condition. Self-with-Other condition induced a significant extension of the space judged as "Near" as compared to both the Selfwith- Object condition and the Self condition. Such extension was observed also in Exp. 2 in the Self-with-Dummy condition. Results suggest that the presence of others impacts on our perception of extrapersonal space. This effect holds also when the other is a human-like wooden dummy, suggesting that structural and morphological shapes resembling human bodies are sufficient conditions for the effect to occur. Conclusions: The observed extension of the portion of space judged as near could represent a wider portion of "accessible" space, thus an advantage in the struggle to survive in presence of other potential competing individuals