Lateral masking as a determinant of global dominance.

The term compound letter refers to a large (global) letter made up of small (local) letters. Reaction time to identify local letters is longer when local and global letters are different than when they are the same (the global dominance effect). The possible contribution of lateral masking to this effect was investigated. Lateral masking denotes reduced probability of identifying a stimulus when it is closely surrounded by other stimuli (as is the case for the local items in a compound stimulus). Three experiments were conducted in which the dependent measure was percentage of correct responses, rather than reaction time. In experiment 1 compound letters were used; accuracy of performance yielded evidence of global dominance such as obtained with reaction time measures. In experiments 2 and 3 the strength of lateral masking in geometrical forms was varied by varying the density of their component items. In agreement with earlier suggestions based on indirect evidence, the results directly implicated lateral masking as an important determinant of global dominance. However, lateral masking could not account fully for the experimental outcome. Factors beyond lateral masking, such as global precedence in the processing sequence or inhibitory interactions among low and high spatial-frequency components of the compound images are required in order to provide a comprehensive account of global dominance effects.     

Functional representation of 3d space in endogenous attention shifts

The aim of this study was to explore whether the attentional system, as far as an endogenous orienting is concerned, allocates resources along the sagittal plane and whether such a process is affected by, and is likely to be based on, different functional representations of 3D space in the brain. Several models make a main action-based distinction between representations of peripersonal space and of those extrapersonal space. Accordingly, if attention has to move from one representation to another, it should be possible to observe a decrease in performance during such a transition. To test this hypothesis three experiments were run in which participants performed a cued detection task. Cue stimuli were informative and were centrally located around the fixation point. Target stimuli were displayed at four different depth planes. In the first experiment, assuming that the border between the peripersonal space and the extrapersonal space was at 1 m from the observer, half the target stimuli were located in the peripersonal space and half in the extrapersonal space. The fixation point was located at 1 m from the observer. In the second experiment, the fixation point was moved at 2 m from the observer in order to rule out the possible effects of ocular motor programming. In the third experiment, in order to rule out effects related to the spatial layout of target stimuli (i.e., centre of mass effect) two target stimuli were located in the peripersonal space and six in the extrapersonal space. In all the experiments, besides a validity effect, we observed greater reaction times when attention shift was across spatial representations than when it was within the same representation. The implications for action-oriented models of attention are discussed.     

Beyond Single-Mindedness: A Figure-Ground Reversal for the Cognitive Sciences

A fundamental fact about human minds is that they are never truly alone: all minds are steeped in situated interaction. That social interaction matters is recognized by any experimentalist who seeks to exclude its influence by studying individuals in isolation. On this view, interaction complicates cognition. Here, we explore the more radical stance that interaction co-constitutes cognition: that we benefit from looking beyond single minds toward cognition as a process involving interacting minds. All around the cognitive sciences, there are approaches that put interaction center stage. Their diverse and pluralistic origins may obscure the fact that collectively, they harbor insights and methods that can respecify foundational assumptions and fuel novel interdisciplinary work. What might the cognitive sciences gain from stronger interactional foundations? This represents, we believe, one of the key questions for the future. Writing as a transdisciplinary collective assembled from across the classic cognitive science hexagon and beyond, we highlight the opportunity for a figure-ground reversal that puts interaction at the heart of cognition. The interactive stance is a way of seeing that deserves to be a key part of the conceptual toolkit of cognitive scientists.     

Naïve chicks do not prefer objects with stable body orientation,though they may prefer behavioural variability

Animal Cognition - Domestic chicks (Gallus gallus domesticus) have been widely used as a model to study the motion cues that allow visually naïve organisms to detect animate agents shortly...