Academic journal article Memory & Cognition

Direct and Indirect Effects of Action on Object Classification

Academic journal article Memory & Cognition

Direct and Indirect Effects of Action on Object Classification

Article excerpt

We report three experiments in which name verification responses to either objects (Experiments 1 and 2) or hand movements (Experiment 3) were compared with action decisions, where participants verified whether an object is typically used in the way described by a verbal label. In Experiments 1 and 2, we report that action decisions show more consistent and larger effects of the congruency of either a handgrip or a type of movement than do name verification responses, although there was some effect of the congruency of the handgrip on name verification. In Experiment 3, we demonstrate that the congruency of the object being moved affects both action and name verification responses to hand movements. We discuss the data relative to accounts of how actions and names are accessed by visually presented objects and in relation to work on the information called upon in classification tasks.

Dual Routes to Action

In our everyday lives, we frequently perform actions that are directed at the objects that surround us. These actions involve online guidance of our effectors in response to objects, plus the selection of the appropriate category to which the action belongs (e.g., drinking from a cup, rather than using it to brush a crumb from a table). This article is concerned with how such categories of action are selected for visually presented objects. Traditionally, theories have stressed that the retrieval of an action is guided by access to semantic knowledge based on an object's associations and its abstract function (e.g., Ochipa, Rothi, & Heilman, 1992; Roy & Square, 1985). For instance, a cup activates the action of drinking through access to semantic knowledge based on our prior associations with how cups are used and what they are used for. However, there is also increasing neuropsychological and experimental evidence that action is evoked by the visual properties of objects in a relatively direct way, without the necessary involvement of semantic (associative) memory (see Humphreys, 2001, and Humphreys & Riddoch, 2003, for reviews; also see Barsalou, 1999, for a similar view derived from a different literature). This evidence provides the backdrop for the present study, in which some of the properties of a putative direct route to action from vision were examined.

Neuropsychological evidence. There is considerable neuropsychological evidence for a relatively direct influence of the visual properties of objects when actions are made to them, as compared with cases in which semantic information is retrieved. This evidence comes primarily from studies of the syndromes of optic aphasia, semantic dementia, and apraxia. Optic aphasia is characterized as an apparently modality-specific naming disorder in which patients are poor at naming visually presented objects, as compared with when they name definitions (e.g., Beauvois, 1982; Coslett & Saffran. 1992; Hillis & Caramazza, 1995; Lhermitte & Beauvois. 1973; Manning & Campbell, 1992; Riddoch & Humphreys, 1987). Despite their poor naming performance, such patients are relatively good at making appropriate gestures to objects. Such gestures have usually been interpreted as indicating spared recognition. However, detailed analyses have suggested that visual recognition (and access to semantic knowledge) can be disrupted. For example, J.B., the patient reported by Riddoch and Humphreys, was impaired at matching associatively related objects (e.g., hammer and nail vs. wrench). In contrast to his poor matching performance with vision, J.B. could match items from their names. Thus, semantic knowledge (from names) was relatively intact, but there was poor access to this knowledge with vision. To account for J.B.'s good gesturing to visually presented objects, Riddoch and Humphreys proposed that his gestures could be based on direct associations between objects and actions, which operated despite his poor access to semantics from objects. …

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