Impact of action planning on spatial perception: Attention matters

Previous research suggested that perception of spatial location is biased towards spatial goals of planned hand movements. In the present study I show that an analogous perceptual distortion can be observed if attention is paid to a spatial location in the absence of planning a hand movement. Participants judged the position of a target during preparation of a mouse movement, the end point of which could deviate from the target by a varying degree in Exp. 1. Judgments of target position were systematically affected by movement characteristics consistent with perceptual assimilation between the target and the planned movement goal. This effect was neither due to an impact of motor execution on judgments (Exp. 2) nor due to characteristics of the movement cues or of certain target positions (Exp. 3, Exp. 5A). When the task included deployment of attention to spatial positions (former movement goals) in preparation for a secondary perceptual task, an effect emerged that was comparable with the bias associated with movement planning (Exp. 4, Exp. 5B). These results indicate that visual distortions accompanying manipulations of variables related to action could be mediated by attentional mechanisms.     

The effect of pre-cueing on spatial attention across perception and action

It is well established that processes of perception and action interact. A key question concerns the role of attention in the interaction between perception-action processes. We tested the hypothesis that spatial attention is shared by perception and action. We created a dual-task paradigm: In one task, spatial information is relevant for perception (spatial-input task) but not for action, and in a second task, spatial information is relevant for action (spatial-output task) but not for perception. We used endogenous pre-cueing, with two between-subjects conditions: In one condition the cue was predictive only for the target location in the spatial-input task; in a second condition the cue was predictive only for the location of the response in the spatial-output task. In both conditions, the cueing equally affected both tasks, regardless of the information conveyed by the cue. This finding directly supports the shared input-output attention hypothesis.     

Peripersonal perception in action

Philosophy of perception is guilty of focusing on the perception of far space, neglecting the possibility that the perception of the space immediately surrounding the body, which is known as peripersonal space, displays different properties. Peripersonal space is the space in which the world is literally at hand for interaction. It is also the space in which the world can become threatening and dangerous, requiring protective behaviours. Recent research in cognitive neuroscience has yielded a vast array of discoveries on the multisensory and sensorimotor specificities of the processing of peripersonal space. Yet very little has been done on their philosophical implications. Here I will raise the following question: in what manner does the visual experience of a big rock close to my foot differ from the visual experience of the moon in the sky?

     

Infant perception of a manual pick-up event

Manual pick-up of an object is a simple causal event frequently observed by infants. A habituation-recovery of looking technique with filmed stimuli is used in experiments which seek to investigate aspects of the perception and encoding of such events in infants. In the first study with 28-week-olds, it is found that ‘lateral mirror-image’ pick-ups are hardly discriminable, while a change in the contact relation of hand and object is readily discriminable. In the second, again with 28-week-olds, the discriminability of the contact relation appears to be specific to a dynamic context involving a hand (rather than another inanimate object). The results of a further experiment make it appear unlikely that the previous results were simply due to the partial occlusion of the picked-up object produced by the grasping. The implications of these results for infant perception of causality are briefly considered.     

Stratification in perception and action

Summary This paper discusses the concept of stratification, in the sense of levels of analysis and levels of control, in relation to human perception and performance. It is contended that functional analysis is the proper level of analysis for the domain of perception and action. This is illustrated by means of models of cognitive energetics and motor control. The functional level of analysis can be situated in between the level of symbolic representations and the level of neurophysiological mechanisms. It is also argued that the concept of levels of control provides a way of integrating or relating ecological and information-processing approaches to psychology, in the sense that ecological psychology is concerned with lower and more peripheral levels of control (coordinative structures). Finally, some remarks are made on the relation between cognition and perception and action, drawing on Piaget, and it is proposed that the concept of schema is more appropriate for the domain of perception and action than is the notion of symbolic representations.     

Using temporal order to identify spatial reference frames

A new method for identifying spatial reference frames is described and applied to the study of spatial span. In this method, a spatial sequence is displayed in relation to two reference frames that move relative to each other, so that different temporal orders are described in each reference frame. As applied to spatial span, a sequence of dots was displayed on a rectangular template that moved relative to the computer screen and the observer. Three experiments showed that the choice of reference frame is influenced by prior conditions, the size of the template, and the presence of an alternative stationary reference frame. Recall was impaired (1) when the template moved, suggesting that movement interference occurred, and (2) with increasing template size, but only if the template was used as the reference frame.     

Haptic perception of spatial relations

There are some indications that haptic space like visual space is not Euclidean (e.g. Blumenfeld, 1937 Acta Psychologica 2 125-174). In a series of experiments, we investigated the haptic perception of spatial relations in a systematic way. We restricted ourselves to a horizontal plane at waist height. Blindfolded subjects were asked to perform three tasks with their right hand: (i) a reference bar was presented under four different orientations and subjects were asked to rotate a test bar such that it felt to be parallel to the reference bar; (ii) subjects had to rotate two test bars in such a way that they felt collinear; (iii) subjects had to point a test bar in the direction of a marker. Bars and marker could appear at nine different locations. In all experiments large systematic deviations (up to 40 degrees) were made. The deviations strongly correlated with horizontal (right-left) but not with vertical (forward-backward) distance. Subjects showed qualitatively identical trends but the size of the deviations was strongly subject-dependent. In addition, a significant haptic oblique effect was found. These results provide strong evidence that haptic space in non-Euclidean.     

Distance perception across spatial discontinuities

We investigated the use of nested contact relations in perceiving the relative distance of locations on discontinuous surfaces. Observers viewed computer-generated displays under monocular static conditions and adjusted a marker to match the perceived distance of a cube. The marker and cube were raised above the ground by two different platforms separated by a gap. The relative heights and distances of the platforms were varied. We found the following: (1) When spatially discontinuous surfaces are coplanar, locations of objects resting on these surfaces appear to be compared directly, bypassing relations with the underlying ground plane. (2) Spatial displacement between the platforms produces a bias, in the direction of the displacement, in the perceived relative locations of objects resting on the platforms. This suggests that local spatial relations between objects and their platforms are only partially integrated with more global spatial relations between the discontinuous surfaces of the platforms.     

Off-line authorship effects in action perception

Does the perception of our actions differ from the perception of other individuals' actions when we observe them, like other individual's actions, in an offline perspective? Previous studies, using recognition as well as prediction judgments, suggest that it does even if the stimulus information is reduced to a single moving point-light. Here, we assessed whether this difference also affects the timing of actions. This was tested in two experiments, using a specific synchronization task. After some practice, self-generated action events were anticipated faster than other action events, provided that the anticipation could not be accomplished sufficiently well on the basis of easily detectable cues. The results are discussed with regard to the previous findings of off-line authorship effects in action perception.     

Frames of reference in spatial span

In four experiments, a computerized Corsi-like paradigm was used to assess which of the many reference frames are used in visuospatial short-term memory. By varying the relative orientation (slanted +/–45° or in an upright position) of the head and the displays, we modulate the utility of the allocentric, egocentric (eye- and head-centred), and template-centred reference frames. The results of all experiments showed the crucial importance of the gravitational allocentric reference frames while using visuospatial short-term memory to retain a spatial sequence of elements. The results also provide some support for a mental rotation process involved in recognition following angular displacement of a multi-item display.     

The seeds of spatial grammar in the manual modality

Sign languages modulate the production of signs in space and use this spatial modulation to refer back to entities—to maintain coreference. We ask here whether spatial modulation is so fundamental to language in the manual modality that it will be invented by individuals asked to create gestures on the spot. English speakers were asked to describe vignettes under 2 conditions: using gesture without speech, and using speech with spontaneous gestures. When using gesture alone, adults placed gestures for particular entities in non-neutral locations and then used those locations to refer back to the entities. When using gesture plus speech, adults also produced gestures in non-neutral locations but used the locations coreferentially far less often. When gesture is forced to take on the full burden of communication, it exploits space for coreference. Coreference thus appears to be a resilient property of language, likely to emerge in communication systems no matter how simple.     

Frames of reference in spatial span

In four experiments, a computerized Corsi-like paradigm was used to assess which of the many reference frames are used in visuospatial short-term memory. By varying the relative orientation (slanted +/-45° or in an upright position) of the head and the displays, we modulate the utility of the allocentric, egocentric (eye- and head-centred), and template-centred reference frames. The results of all experiments showed the crucial importance of the gravitational allocentric reference frames while using visuospatial short-term memory to retain a spatial sequence of elements. The results also provide some support for a mental rotation process involved in recognition following angular displacement of a multi-item display.     

Temporal perception in joint action: This is MY action

Here we investigated the temporal perception of self- and other-generated actions during sequential joint actions. Participants judged the perceived time of two events, the first triggered by the participant and the second by another agent, during a cooperative or competitive interaction, or by an unspecified mechanical cause. Results showed that participants perceived self-generated events as shifted earlier in time (anticipation temporal judgment bias) and non-self-generated events as shifted later in time (repulsion temporal judgment bias). This latter effect was observed independently from the kind of cause (i.e., agentive or mechanical) or interaction (i.e., cooperative or competitive). We suggest that this might represent a mental process which allows discriminating events that cannot plausibly be linked to one’s own action. When an event immediately follows a self-generated one, temporal judgment biases operate as self-serving biases in order to separate self-generated events from events of another physical causality.     

Representing serial action and perception

This article presents a review on the representational base of sequence learning in the serial reaction time task. The first part of the article addresses the major questions and challenges that underlie the debate on implicit and explicit learning. In the second part, the informational content that underlies sequence representations is reviewed. The latter issue has produced a rich and equivocal literature. A taxonomy illustrates that substantial support exists for associations between successive stimulus features, between successive response features, and between successive response-to-stimulus compounds. We suggest that sequence learning is not predetermined with respect to one particular type of information but, rather, develops according to an overall principle of activation contingent on task characteristics. Moreover, substantiating such an integrative approach is proposed by a synthesis with the dual-system model (Keele, Ivry, Mayr, Hazeltine, & Heuer, 2003).     

Temporal and spatial characteristics of attention to facilitate manual and eye-movement responses

Previous investigation found that the speed of saccadic eye movements is enhanced when a temporal interval (gap) is introduced between the disappearance of a foveal fixation mark and the appearance of a peripheral target (the gap paradigm). Attention was shown to be involved in the gap paradigm. Here, we investigated relevant temporal and spatial characteristics of attention, manipulating central fixation marks and peripheral targets. Results from three experiments indicate that (i) the speed of manual and eye-movement detection is accelerated when a fixation mark changes abruptly (in less than 100 ms) before its termination in the gap paradigm; (ii) the speed is further accelerated when a peripheral target location is pre-cued; (iii) sufficient time for fixation (1000 ms) is necessary for the facilitation. These results suggest that fast and transient attention at the fixation spot facilitates attentional disengagement process that urges a spatial-orienting mechanism. Sustained attention is required in the engagement process during the fixation.