What is peripersonal space? An examination of unresolved empirical issues and emerging findings.

Findings from diverse fields of study, including neuroscience, psychology, zoology, and sociology, demonstrate that human and non-human primates maintain a representation of the space immediately surrounding the body, known as peripersonal space (PPS). However, progress in this field has been hampered by the lack of an agreed upon definition of PPS. Since the beginning of its formal study, scientists have argued that PPS plays a crucial role in both defensive and non-defensive actions. Yet consensus is lacking about the cognitive and neural instantiation of these functions. In particular, researchers have begun to ask whether a single, unified system of spatial-attentional resources supports both the defensive and non-defensive functions of PPS or, rather, whether there are multiple, independent systems. Moreover, there are open questions about the specificity of PPS. For example: Does PPS dissociate from other well-known phenomena such as personal space and the body schema? Finally, emerging research has brought attention to important questions about individual differences in the flexibility of PPS and the distribution of PPS in front compared to behind the body. In this advanced review, we shed light on questions about the nature of PPS, offering answers when the research permits or providing recommendations for achieving answers in future research. In so doing, we lay the groundwork for a comprehensive definition of PPS. This article is categorized under: Cognitive Biology > Evolutionary Roots of Cognition Psychology > Attention Psychology > Perception and Psychophysics Neuroscience > Plasticity.

Children's use of comparison and function in novel object categorization.

Although young children often rely on salient perceptual cues, such as shape, when categorizing novel objects, children eventually shift towards deeper relational reasoning about category membership. This study investigates what information young children use to classify novel instances of familiar categories. Specifically, we investigated two sources of information that have the potential to facilitate the classification of novel exemplars: (1) comparison of familiar category instances, and (2) attention to function information that might direct children's attention to functionally relevant perceptual features. Across two experiments, we found that comparing two perceptually similar category members-particularly when function information was also highlighted-led children to discover non-obvious relational features that supported their categorization of novel category instances. Together, these findings demonstrate that comparison may aid in novel object categorization by heightening the salience of less obvious, yet functionally relevant, relational structures that support conceptual reasoning.

Individual Differences in the Flexibility of Peripersonal Space.

The current study investigated individual differences in the flexibility of peripersonal space (i.e., representational space near the body), specifically in relation to trait claustrophobic fear (i.e., fear of suffocating or being physically restricted). Participants completed a line bisection task with either a laser pointer (Laser condition), allowing for a baseline measure of the size of one's peripersonal space, or a stick (Stick condition), which produces expansion of one's peripersonal space. Our results revealed that individuals high in claustrophobic fear had larger peripersonal spaces than those lower in claustrophobic fear, replicating previous research. We also found that, whereas individuals low in claustrophobic fear demonstrated the expected expansion of peripersonal space in the Stick condition, individuals high in claustrophobic fear showed less expansion, suggesting decreased flexibility. We discuss these findings in relation to the defensive function of peripersonal space and reduced attentional flexibility associated with trait anxieties.

Labels affect preschoolers' tool-based scale errors.

Scale errors offer a unique context in which to examine the interdependencies between language and action. Here, we manipulated the presence of labels in a tool-based paradigm previously shown to elicit high rates of scale errors. We predicted that labels would increase children's scale errors with tools by directing attention to shape, function, and category membership. Children between the ages of 2 and 3years were introduced to an apparatus and shown how to produce its function using a tool (e.g., scooping a toy fish from an aquarium using a net). In each of two test trials, children were asked to choose between two novel tools to complete the same task: one that was a large non-functional version of the tool presented in training and one novel functional object (different in shape). A total of four tool-apparatus sets were tested. The results indicated that without labels, scale errors decreased over the two test trials. In contrast, when labels were present, scale errors remained high in the second test trial. We interpret these findings as evidence that linguistic cues can influence children's action-based errors with tools.