The current study extended previous works demonstrating the effect of action relations between objects on object identification in neuropsychological populations (Humphreys &
Riddoch, 2001; Humphreys, Riddoch, Forti, & Ackroyd, 2004; Humphreys, Wulff, Yoon, &
Riddoch, 2010; Riddoch et al., 2003) and healthy participants (Roberts & Humphreys, 2010a, 2010b, 2011a, 2011b). Our results illustrated that responses to different objects were modulated by the scene context in opposite ways – responses to objects active in the action being facilitated and responses to passive objects being suppressed. The work points to the competition between affordances of action related objects, and the importance of contextual information in affordance selection in multi-object visual scenes.
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Chapter 3
What gives the active objects the dominance in implied between-object actions?
Abstract
Chapter 2 established the automatic processing of implied between-object actions when the object pairs are task irrelevant, and identified two effects of the implied actions between objects on response selection. Both effects suggested dominance of the active objects in implied between-object actions. This chapter aimed to identify properties of the object pairs that give the active objects this dominance. We used unfamiliar and untypical active-passive object pairs in the same paradigm described in Chapter 2 to examine the contribution from familiarity/typicality of object pairing (e.g. a saw and a bowl; Experiment 1), and used passive-passive object pairs (formed by replacing the active with a passive object in a given pair, e.g. a cup-nail vs. bowl-nail) to examine the impact of the presence of active objects and of action-related object structures (Experiment 2). Further, this chapter clarified the immediate response to such features. The involvement of motor activation was examined in Experiment 3 by requiring reaching and grasping responses. Unfamiliar active-passive object pairs (Experiment 1) and passive-passive object pairs (Experiment 2) with handles replicated the effects observed with familiar object pairs, but these effects were absent when the passive-passive object pairs did not have a handle. The reaching-and-grasping task did not alter the effects of implied between-object actions either. These results suggested that the effect of implied between-object actions can be driven by the processing of action-related structures of objects, which activated the abstract instead of specific action codes.
Keywords: stimulus-response compatibility effect, configural processing, implied actions, action possibility, affordance
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3.1 Introduction
Experiments reported in Chapter 2 identified two behavioural signatures of the implied actions between objects: the inhibitory effects on responses aligned with the passive objects and the advantage for active objects. Both suggest dominance of the active objects in implied between-object actions. One striking characteristic of the findings is the automatic extraction of distinct functional roles (active vs. passive) in the object-pair. Given that the implied actions are highly synthetic and learned, such automaticity is surprising. A question naturally follows is what the underlying mechanisms of this seemingly sophisticated process are. For instance, it is possible that the advantage for the active objects were generated by recognizing familiar pairs of objects which afford well-learnt actions. It is also possible that selection between objects was made by identifying certain objects which are of “higher”
functional value, rather than by identifying the objects as a pair. For example the presence of an active object might be crucial because they can be seen as more usable than the passive object. Yet another alternative could be that the implied between-object actions are determined without identifying the objects, but by locating the action-related object structures, e. g. handles. For instance, the spoon stipulates the stirring due to its handle making it an active object, while the lack of any obvious action-related structures on the bowl makes it a passive object. In sum, the present chapter asks the question what mechanisms lead to the dominance of the active objects in our findings.
Experiment 1 tests the influence of the identification of object pairs by re-pairing the active with passive objects, e.g. a saw is paired with a bowl thus reducing the familiarity of object pairs. Hence if the effects reported in Chapter 2 were generated by the recognition of familiar pairs of objects or the familiar actions between them, the unfamiliar object pairing would eliminate or reduce the influence of interacting co-locations between objects.
Alternatively, if the effects may be due to “high” functional values of the individual objects
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(e.g. the active objects), then we should be able to replicate the effect. Experiment 2 examines further the possible influence from the presence of particular objects of “high”
functional values by pairing larger and smaller objects previously used as passive objects (e.g. a bowl and a screw) and treated the larger one as “active”. As these pairs don’t include real active objects, the effects found in Chapter 2 should be eliminated if the functional-value exclusive to the active objects matters. In addition, some of the assigned “active” objects possess handles while others do not. We expect to replicate the findings of Chapter 2 with
“active” objects having handles, but not with the handle-less ones, if the advantage for active objects was due to action-related features. In addition, by treating the larger objects as active objects in each pair, Experiment 2 also tests a possible confounding factor in the experiments of Chapter 2. In these experiments the active objects were generally larger than the passive objects (with exceptions, e.g. a bottle opener and a bottle). Consequently, if the passive-passive object pairs in Experiment 2 cannot produce the same response pattern observed in Chapter 2, it is likely that the two effects observed in Chapter 2 were generated by factors other than relative size difference between the active and the passive objects.
To foreshadow the results of Experiment 1 and 2, we found effects of implied between-object actions in Experiment 1 and for some pairs of between-objects in Experiment 2 (to be detailed below), which argues against the importance of the familiarity of object pairings and the presence of the active objects as such. Further, Experiment 2 found that the effects of implied between-object actions can only be replicated when the assigned “active” object has a handle, and that the size difference between objects is unlikely to be the cause of these effects. This suggests that the action-related object parts can be a critical source of the object dominance in implied between-object actions.
Experiment 4, Chapter 2 suggested that the effects of implied between-object actions are the result of activated abstract action codes as the effects were independent of the motor program for the task responses (left-right key presses vs. index-middle finger). However,
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given the importance of action-related structures of objects found in the present chapter, it is possible that the reach and grasp action afforded by the objects is also facilitated by these structures. In other words, the effects of between-objects actions may benefit from the activation of the exact afforded actions, as well as by abstract response codes. Then the effects should be enhanced by a reaching-and-grasping task. In Experiment 3 the participants were required to reach and grasp a joystick with the left or right hand, depending on the shape of the central target. Even though this task does not exactly replicate the real action towards the presented objects it still resembles more the afforded actions than a key-press task.
The basic paradigm and the task setting of experiments in Chapter 3 are the same to that in Chapter 2, with the main interest being the interaction between co-location (correct vs.
incorrect) and response compatibility (active vs. passive objects). Based on the findings of Chapter 2 that co-location does not reliably affect responses aligned with the active objects, experiments in Chapter 3 only included the incorrect co-location condition in which the orientation of the active objects was manipulated.