Visual search by action category

Abstract

Humans are sensitive to different categories of actions due to their importance in social interactions. However, biological motion research has been heavily tilted toward the use of walking figures. Employing point-light animations (PLAs) derived from motion capture data, we investigated how different activities (boxing, dancing, running, and walking) related to each other during action perception, using a visual search task. We found that differentiating between actions requires attention in general. However, a search asymmetry was revealed between boxers and walkers, i.e., searching for a boxer among walkers is more efficient than searching for a walker among boxers, suggesting the existence of a critical feature for categorizing these two actions. The similarities among the various actions were derived from hierarchical clustering of search slopes. Walking and running proved to be most related, followed by dancing and then boxing. Signal detection theory was used to conduct a non-parametric ROC analysis, revealing that human performance in visual search is not fully explained by low-level motion information.

Perception of Human Interaction Based on Motion Trajectories: From Aerial Videos to Decontextualized Animations

“…The fairly fast, automatic, irresistible, and highly stimulus‐driven impressions about animacy and interactivity are largely perceptual in nature. This result is consistent with the literature on causal perception (Peng, Thurman, & Lu, ; Scholl & Tremoulet, ) and biological motion perception (Johansson, ; Su, van Boxtel, & Lu, ; Thurman & Lu, ; van Boxtel & Lu, ). Hence, the detection of interactivity between agents is likely to be processed as in the proposed model without the explicit modeling of intention and goals.…”

Do People “Pop Out”?

“…Search tasks have been applied to biological motion stimuli such as point-light walkers displaying human or animal movements, but to date, no pop-out search has been demonstrated (e.g., [ 32 ], [ 33 ], [ 34 ]). Similarly, it is also effortful to search for particular human actions (e.g., boxing) amidst other distractor actions (e.g., marching; [ 33 ]).…”

Communicative interactions in point-light displays: Choosing among multiple response alternatives

“…Human observers have no trouble identifying what an actor is doing in a given point-light display (e.g., Dittrich, 1993; Vanrie & Verfaillie, 2004). Even when the range of potential activities is quite large, they readily recognize individual actions and the associated emotions (Alaerts, Nackaerts, Meyns, Swinnen, & Wenderoth, 2011; Brownlow, Dixon, Egbert, & Radcliffe, 1997; Dittrich, Troscianko, Lea, & Morgan, 1996; Pollick, Paterson, Bruderlin, & Sanford, 2001; van Boxtel & Lu, 2011; Walk & Homan, 1984), are able to understand the intentions of the actor, and can detect a violation of his/her expectations (Runeson & Frykholm, 1983). …”