Neuropsychological evidence for visual- and motor-based affordance: Effects of reference frame and object–hand congruence.

Abstract

Two experiments are reported that use patients with visual extinction to examine how visual attention is influenced by action information in images. In Experiment 1 patients saw images of objects that were either correctly or incorrectly colocated for action, with the objects held by hands that were congruent or incongruent with those used premorbidly by the patients. The images were also shown from a 1st- and 3rd-person perspective. There was an overall reduction in extinction for objects colocated for action. In addition, there was an extra benefit when the objects were held in hands congruent with those used by the patients and when the objects were seen from a 1st-person perspective. This last result fits with an effect of motor simulation, over and above a purely visual effect based on positioning objects correctly for action. Experiment 2 showed that effects of hand congruence could emerge with images depicted from a 3rd-person perspective when patients saw themselves holding the objects. The data indicate 2 effects of action information on extinction: (a) an effect of colocating objects for action, which does not depend on a self-reference frame (a visual effect), and (b) an effect sensitive to object-hand congruence, which does depend on a self-reference frame (a motor-based effect). The self-reference frame is induced when stimuli are viewed from a 1st-person perspective and when an image of the self is seen from a 3rd-person perspective. Both visual and motor-based effects of action information facilitate the spread of attention across objects.

Action relations facilitate the identification of briefly-presented objects

“…These findings are also consistent with evidence that preparing to make a reaching movement towards a target improves perception of stimuli presented at that location (Deubel et al, 1998). Interestingly, Humphreys, Wulff, Yoon, and Riddoch (2010) have reported that orienting active objects for the dominant hand can affect extinction, too. Patients showed less extinction with objects positioned for action when the active object was aligned with the hand that the patient would normally use for that object in the action.…”

“…The data were then analysed according to whether the active object was oriented for use with the viewer's dominant hand (to the right for right-handed viewers and to the left for left-handed viewers) or for use with their other hand. The results show that compatibility between the handedness of participants and the left/right location of the objects affected identification of the active object, but not the passive object, consistent with our interpretation that object affordances are enhanced when the objects are oriented for use by the dominant hand (see also Humphreys et al, 2010). However, an alternative explanation is that it is the location of the object in the right or left hemifield that influences performance.…”

“…In extinction, the effects of orienting active objects to the patient's dominant hand arise only when the objects are shown from the participant's (egocentric) reference frame (as if the participant is using the objects). On the other hand, effects of co-locating objects for action occur both when objects are seen from the patient's reference frame and when they are seen from the opposite position (from an allocentric frame, looking across a table to an actor; Humphreys et al, 2010). In temporal order judgements, then, effects of the visuomotor response can be shown in the absence of perceptual grouping, while in extinction, effects of perceptual grouping can be demonstrated when the visuomotor response effect is reduced (stimuli shown from an allocentric frame).…”

Attending to the possibilities of action

“…Importantly, our results show that this visual response is separate from the motor-based simulation to stimuli congruent with the standard motor action. We suggest that this evoked motor response feeds back to enhance visual processing and, based on the results with visual extinction [27], this can enable stimuli to be selected together.…”

“…Neuropsychological evidence for this second, motor component comes from a study by Humphreys et al [27]. They tested the effects of action relations on extinction and varied whether the objects appeared either from the patient's own view or from a third-person perspective, and whether the position of the active object aligned with the hand that the patient would have used for the action (e.g.…”