Representational momentum and the human face : an empirical note

Recent evidence suggests that observers may anticipate the future emotional state of an actor when viewing dynamic expressions of emotion, consistent with the notion of representational momentum. The current paper presents data that conflicts with these previous studies, finding instead that memory for the final frame of an emotional video tends to be shifted back in the direction of the first frame. While simple methodological issues may explain this difference (e.g., the use of morph sequences in previous studies versus naturalistic expressions here) a more theoretically interesting possibility is also considered. Specifically, recent studies of ensemble representations have shown that observes can rapidly extract the average expression from a display of up to 20 faces. It is suggested that the need to predict versus the need to maintain a stable estimate of the current state often compete when we interact with dynamic stimuli. Our memory for the final expression on an emotional face may be particularly sensitive to task demands and response timing, thus coming to reflect different solutions to this anticipation-averaging conflict depending on the precise experimental scenario.peer-reviewe

Studies in the Terpenoid Field

Abstract Not Provided

Action perception : seeing the world through a moving body

Recent evidence suggests that the acquisition of new motor skills can directly influence later visual perception even when an observer's eyes remain ‘wide shut’ during learning.peer-reviewe

Does action disrupt Multiple Object Tracking (MOT)?

While the relationship between action and focused attention has been well-studied, less is known about the ability to divide attention while acting. In the current paper we explore this issue using the multiple object tracking (MOT) paradigm (Pylyshyn & Storm, 1988). We asked whether planning and executing a display-relevant action during tracking would substantially affect the ability track and later identify targets. In all trials the primary task was to track 4 targets among a set of 8 identical objects. Several times during each trial, one object, selected at random, briefly changed colour. In the baseline MOT trials, these changes were ignored. During active trials, each changed object had to be quickly touched. On a given trial, changed objects were either from the tracking set or were selected at random from all 8 objects. Although there was a small dual-task cost, the need to act did not substantially impair tracking under either touch condition.peer-reviewe

Haptic choice blindness

Choice blindness is the failure to notice a mismatch between intention and outcome when making decisions. It is unknown whether choice blindness occurs when participants have extended interaction with real objects. Here, we examined the case when objects could be touched but not seen. Participants examined pairs of common, everyday objects inside a specially constructed box where a silent turntable was used to switch objects between initial choice and later justification. For similar pairs of objects, we found detection rates of around 22%, consistent with previous studies of choice blindness. For pairs consisting of more distinctive exemplars, the detection rate rose to 70%. Our results indicate that choice blindness does occur after haptic interaction with real objects, but is strongly modulated by similarity.peer-reviewe

Idiosyncratic body motion influences person recognition

Person recognition is an important human ability. The main source of information we use to recognize people is the face. However, there is a variety of other information that contributes to person recognition, and the face is almost exclusively perceived in the presence of a moving body. Here, we used recent motion capture and computer animation techniques to quantitatively explore the impact of body motion on person recognition. Participants were familiarized with two animated avatars each performing the same basic sequence of karate actions with slight idiosyncratic differences in the body movements. The body of both avatars was the same, but they differed in their facial identity and body movements. In a subsequent recognition task, participants saw avatars whose facial identity consisted of morphs between the learned individuals. Across trials, each avatar was seen animated with sequences taken from both of the learned movement patterns. Participants were asked to judge the identity of the avatars. The avatars that contained the two original heads were predominantly identified by their facial identity regardless of body motion. More importantly however, participants identified the ambiguous avatar primarily based on its body motion. This clearly shows that body motion can affect the perception of identity. Our results also highlight the importance of taking into account the face in the context of a body rather than solely concentrating on facial information for person recognition.peer-reviewe

Matching biological motion at extreme distances

The goal of the current paper was to determine the maximum distance at which an actor could be placed so that an observer would still be able to interpret their behavior. Although we know a great deal about the limits of action perception, particularly through studies of biological motion processing, this question of distance has not been previously documented. We began by reviewing the sizes of point-light figures used in 100 previous studies of biological motion. We found that with an average figure height of 6.68 visual angle, actors were effectively 15 m from the observer, assuming average physical height of 1.75 m. No previous studies had explicitly examined extreme distances. Here, we introduce a new matching task in which we systematically varied the apparent distance of point-light figures relative to a fixed viewing position by manipulating size. Our results suggest that a variety of human actions could potentially be interpreted up to 1000 m away, a distance at which a human figure would subtend only 0.18 visual angle in height. Dynamic figures could be interpreted at further distances than static figures (Experiment 1), and upright figures were similarly processed more efficiently than inverted figures (Experiment 2). We discuss these findings in the context of the processing mechanisms thought to underlie action perception and suggest that the ability to match actions at extreme distance is another example of the robust nature of biological motion processing.peer-reviewe

Motion can amplify the face-inversion effect

The face-inversion effect (FIE) refers to increased response times or error rates for faces that are presented upside-down relative to those seen in a canonical, upright orientation. Here we report one situation in which this FIE can be amplified when observers are shown dynamic facial expressions, rather than static facial expressions. In two experiments observers were asked to assign gender to a random sequence of un-degraded static or moving faces. Each face was seen both upright and inverted. For static images, this task led to little or no effect of inversion. For moving faces, the cost of inversion was a response time increase of approximately 100 ms relative to upright. Motion thus led to a disadvantage in the context of inversion. The fact that such motion could not be ignored in favour of available form cues suggests that dynamic processing may be mandatory. In two control experiments a difference between static and dynamic inversion was not observed for whole-body stimuli or for human-animal decisions. These latter findings suggest that the processing of upside-down movies is not always more difficult for the visual system than the processing of upside-down static images.peer-reviewe

The visual perception of human locomotion

To function adeptly within our environment, we must perceive and interpret the movements of others. What mechanisms underlie our exquisite visual sensitivity to human movement? To address this question, a set of psychophysical studies was conducted to ascertain the temporal characteristics of the visual perception of human locomotion. Subjects viewed a computer-generated point-light walker presented within a mask under conditions of apparent motion. The temporal delay between the display frames as well as the motion characteristics of the mask were varied. With sufficiently long trial durations, performance in a direction discrimination task remained fairly constant across inter-stimulus interval (ISI) when the walker was presented within a random motion mask but increased with ISI when the mask motion duplicated the motion of the walker. This pattern of results suggests that both low-level and high-level visual analyses are involved in the visual perception of human locomotion. These findings are discussed in relation to recent neurophysiological data suggesting that the visual perception of human movement may involve a functional linkage between the visual and motor systems.peer-reviewe