Effects of Object Function on Visual Search in Real-World Scenes

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Witherspoon, Richelle
visual-search , affordance
Our everyday interactions with the world are subject to affordance: the interaction that exists naturally between an object and the action possibilities inherent within it. Object affordances result from complex visuomotor interactions and are reflected in many processes, including reaching and grasping behaviours, distance judgments, and object identification. With the present study we extended current research on the use of affordances in visual searches of arrays to investigate whether guidance by affordance occurs in searches of real-world scenes and is the result of knowledge of target function (Experiment 1), and whether it is integrated with the use of scene context in guidance of search (Experiment 2). To investigate the contribution of object function to guidance by affordance in real-world scenes we tracked participants’ eye movements while they performed visual searches. The target objects were invented objects with invented functions that were learned by the participants prior to beginning search. By providing participants with information about only the features and functions of targets (and not about location) we omitted any effects on search from previously learned associations between the objects and their locations in the scene. This allowed us to examine guidance by affordance independently of traditional contextual effects. In Experiment 1 we compared the searches of participants who learned the functions of the targets to those who learned only the targets’ features. Results showed facilitation of visual search by knowledge of target function as compared against searches in which target function was not known. Experiment 2 compared searches for objects placed in locations congruent and incongruent with their function to show that guidance by affordance is benefitted by knowledge of target function in congruent searches. We concluded that guidance by affordance results from an understanding of the function of an object and the integration of that understanding into an understanding of the context of the scene as a whole
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