Perceptual-motor coordination and adaptation during locomotion: Determinants of prism adaptation in hall exposure

Abstract

Adaptation to prismatic displacement was examined under a number of conditions with locomotion in a hallway exposure. In general, total prism adaptation was inversely related to secondary cognitive load (presence or absence of mental arithmetic) and the relative magnitude of visual and proprioceptive shift depended upon the availability of visible sound sources in the hall environment. When the speaking experimenter was visible to the subject, visual shift was greater than proprioceptive shift, but when the experimenter was not visible and/or was silent, proprioceptive shift was greater than visual shift. No relationship has been detected between locomotion (walking rate) and either prism adaptation or cognitive load. These results are consistent with a model which assumes that the total adaptive response depends upon the available capacity to establish and maintain coordinative linkage between discordant systems, whereas locus of adaptive recalibration depends upon the direction of these coordinative linkages, discordance and adaptation occurring in the guided systemfs). The available capacity for coordinative linkage depends upon cognitive load, whereas the directionality of linkage is independently determined by task structure. Locomotion is assumed to be mediated by a sensorimotor system that does not involve the distorted positional information.The picture of perceptual-motor organization that has emerged from prism-adaptation research is both surprisingly simple and bewilderingly complex. The total adaptive response can usually be described in terms of local adaptive changes in a linear system (Howard, 1971(Howard, , 1982 and additive contributions from the various components of such a serially organized system

Components of prism adaptation in terminal and concurrent exposure: Organization of the eye-hand coordination loop

“…The viability of this view is illustrated by recent investigations (Redding et al, 1985;Redding & Wallace, 1985a, 1985b of prism adaptation during locomotion along hallways. This work suggests that locomotion per se is mediated by an eye-foot movement system utilizing 0p-tical flow information that is unaffected by optical dis-placement of the visual field.…”

“…This work suggests that locomotion per se is mediated by an eye-foot movement system utilizing 0p-tical flow information that is unaffected by optical dis-placement of the visual field. Adaptation to discordance among positional systems (eye-head, eye-hand, and earneck) seems to require that systems be directionally linked in such a way that one system serves as the source of guidance signals for another, with adaptation occurring in the guided system (Redding & Wallace, 1985b, 1987. Moreover, limited central processing capacity (attention) is utilized in establishing and maintaining the directional linkages between discordant systems necessary for adaptation (Redding et al, 1985;Redding & Wallace, 1985a).…”

Perceptual-motor coordination and prism adaptation during locomotion: A control for head posture contributions

“…The second prediction has been validated many times and under a variety of conditions that seem to exclude alternative explanations (see Redding et al, 1985;Redding & Wallace, 1985a). Support for the third prediction comes from the repeated observation that the primary task of walking does not suffer interference from a secondary mental arithmetic task (Redding et al, 1985;Redding & Wallace, 1985a), and from the fact that salient optical flow can support exceedingly high walking speeds without producing any adaptation (Redding & Wallace, 1985b, Experiment 1). Redding and Wallace (1985b, Experiments 2 and 3) provided a test of the fourth prediction by manipulating the availability of auditory stimuli as a source for visuallocational response.…”

“…The hall was the same one used in previous studies (Redding & Wallace, 1985a, 1985b, and there was little human traffic except for the experimenter and subject. However, a restroom located off the hall was the occasion for infrequent pedestrian incursions from other parts of the building, and maintenance personnel also occasionally appeared in the hall.…”

“…The organization of the perceptual-motor system as it is used in many everyday situations may be conceptualized as depicted in Figure 1 (Redding, Clark, & Wallace, 1985;Redding & Wallace, 1985a, 1985b; this is the case, for example, when a person walks a familiar path, such as a hallway, while at the same time engaging in other activities, such as looking for a room number, at a speaking companion, or toward an obstacle just bumped into. Locomotion per se is assumed to be automatically 1 guided via movement channels by Gibson-like optical flow patterns (e.g., Fitch, Tuller, & Turvey, 1982;Lee & Thomson, 1982;Longuet-Higgins & Prazdny, 1980) and does not normally require central processing capacity (i.e., attention) unless nonroutine terrain is encountered.…”