Academic journal article Canadian Journal of Experimental Psychology

Embodied Object Concepts: The Contribution of Structural and Functional Manipulability Depends on Available Visual Information

Academic journal article Canadian Journal of Experimental Psychology

Embodied Object Concepts: The Contribution of Structural and Functional Manipulability Depends on Available Visual Information

Article excerpt

(ProQuest: ... denotes formulae omitted.)

Much of human behavior is driven by the need to identify objects and use them in appropriate contexts. For instance, the way you grasp a hammer, and the things you will do with it. will depend largely on whether you encounter it on a workbench or in a kitchen. According to recent proposals stemming from the embodied (or grounded) cognition literature {e.g., Barsalou, 2008), our ability to identify an object such as a hammer depends on the activation of distributed representations of sensorimotor information in the dorsal stream (see Meyer & Damasio, 2009; for a review see Coodale. 2008). Consistent with the embodied cognition proposal is the finding that the dorsal stream is active when passively viewing manipulable objects (Chao & Martin, 2000; Grezes, Tucker, Armony, Ellis, & Passingham, 2003). Further, these distributed representations support object identification, For example, Wolk, Coslett, and Glosser (2005) reported that patients with visual agnosia, who showed general deficits in identifying visually presented objects, are better at identifying manipulable than nonmanipulable objects; it was argued that the manipulable objects successfully activate action representations in the dorsal stream in these patients and that this activation benefits identification. Behaviorally, Filliter. McMullen, and Westwood (2005) showed that participants identified manipulable objects differently than nonmanipulable (see also Salmon, Matheson, & McMullen, 2014a, 2014b). Overall then, there is both neural and behavioral evidence that the manipulability of objects, represented by dorsal stream activity, supports object identification (though for counter evidence see Bub & Masson, 2010; Proctor & Miles, 2014; Yu, Abrams, & Zacks, 2014).

Recent neuropsychological theories have elaborated on the nature of processing that occurs within the dorsal stream. For instance, Binkofski and Buxbaum (2013) have suggested that there are two subsystems within the dorsal stream, each serving a different action-related purpose. This difference is demonstrated as a double dissociation in neuropsychological patients. While most apraxic patients perform normally when reaching for and grasping objects, they have difficulty pantomiming object-related gestures and show significant impairments when using objects (Buxbaum & Kalénine, 2010). Conversely, patients with optic ataxia are impaired at reaching for and grasping objects but perform normally in gesture/pantomime tasks (Buxbaum & Coslett, 1997, 1998). The observed patterns of performance in patients with lesions to the dorsal stream led Buxbaum and colleagues to conclude that more dorsal regions of the parietal lobe (i.e., dorso-dorsal regions) are important for representing information related to how the hand is shaped during online visually guided grasping, driven primarily by the structural features of objects. Conversely, more ventral regions of the parietal lobe (e.g., ventro-dorsal regions) are important for representing information related to how an object is used in a particular context, driven primarily by the functional features of objects.

The distinction between structural and functional information has also been revealed by others, both neural ly and behaviorally. For instance. Valyear and Çulham (2010) showed that areas of the ventrodorsal stream more strongly activated in response to videos of hands interacting with tools in functional ways compared to nonfunctional, structurally derived ways. Behaviorally, viewing an object as a prime will facilitate grasping that same object when the goal is to grasp it to use (i.e., functional grasp), but not when the goal is to simply move the object (i.e., structural grasp; Valyear, Chapman, Gallivan, Mark, & Çulham, 2011). Similarly, Bub, Masson, and Cree (2008) showed that visually presenting an object prime facilitates producing actions toward a graspasaurus (i. …

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