The Interaction of Space and Time in Cutaneous Perception

102

103

This study addressed the role of proprioceptive and visual cues to body posture during the deployment of tactile spatial attention. Participants made speeded elevation judgments (up vs. down) to vibrotactile targets presented to the finger or thumb of either hand, while attempting to ignore vibrotactile distractors presented to the opposite hand. The first two experiments established the validity of this paradigm and showed that congruency effects were stronger when the target hand was uncertain (Experiment 1) than when it was certain (Experiment 2). Varying the orientation of the hands revealed that these congruency effects were determined by the position of the target and distractor in external space, and not by the particular skin sites stimulated (Experiment 3). Congruency effects increased as the hands were brought closer together in the dark (Experiment 4), demonstrating the role of proprioceptive input in modulating tactile selective attention. This spatial modulation was also demonstrated when a mirror was used to alter the visually perceived separation between the hands (Experiment 5). These results suggest that tactile, spatially selective attention can operate according to an abstract spatial frame of reference, which is significantly modulated by multisensory contributions from both proprioception and vision.

Section: Notescontrasting

confidence: 59%

Tactile selective attention and body posture: Assessing the multisensory contributions of vision and proprioception

Soto‐Faraco

Ronald

Spence

2004

102

103

“…Jones (19'6) found two-point thresholds to decrease with increasing interpulse interval; Wieland (1960) later obtained similar results. Solomonow, Raplee, and Lyman (1978) found two-point thresholds to depend on pulse frequency, time delay, and pulse width, the last two variables interacting.…”

mentioning

confidence: 79%

Electrocutaneous stimulation II. The estimation of distance between two points

Marks

Girvin

Quest

et al. 1982

Using a numerical estimation procedure, subjects judged the perceived distance between pairs of brief electrical stimuli presented over different physical distances, on different body regions, and in different spatial orientations. The skin turns out to be anisotropic, with the same physical separation between electrodes appearing greater on the forehead than on the forearm, greater on the forearm than on the abdomen. Perceived distance also depends on the orientation and, to some extent, on the time relation between the two electrical pulses. Under all conditions, the perceived distance between electrical stimuli was "compressed" as compared with visual distance. These results bear on the design of devices that attempt to transmit information by electrical stimulation of the skin.Having evaluated, in the previous paper of this series (Girvin, Marks, Antunes, Quest, O'Keefe, Ning, & Dobelle, 1982), how several properties of the stimulus influence absolute sensitivity to electrocutaneous stimulation, the specific aim of the experiments reported here is to determine the skin's capacity to represent spatial information. In essence, this study asks: How accurately and how reliably can one perceive the distance between two brief electrical pulses presented in various parts of the body?It has long been known that the skin is not isotropic in its response to mechanical stimulation. More than a century ago, E. H. Weber (1834) observed that the distance between two points touched on the skin seemed greater in some parts of the body (e.g., the face) than in others (e.g., the trunk), and greater when the points were oriented in certain directions (e.g., transversely) than in others (longitudinally). In terms of the two-point threshold, measurements by others (Vierordt, 1869;Weinstein, 1968) conform to Weber's own observations, although, to be sure, two-point thresholds provide

“…It is possible that the difficulty in the TOJ studies stemmed from the fact that people find it difficult to process (or spatially remap) two or more vibrotactile stimuli if they are presented in rapid succession in the crossed posture. This might be due to some form of computational overload or spatiotemporal ambiguity specific to the tactile system (see Shore et al, 2002a, andWeiland, 1960, on this point). Alternatively, the confusion might be caused by differences between the TOJ and the spatial discrimination tasks themselves.…”

Section: Posture Change and Tojsmentioning

confidence: 99%

Multisensory temporal order judgments: When two locations are better than one

Spence

Baddeley

Zampini

et al. 2003

150

In Experiment 1, participants were presented with pairs of stimuli (one visual and the other tactile) from the left and/or right of fixation at varying stimulus onset asynchronies and were required to make unspeeded temporal order judgments (TOJs) regarding which modality was presented first. When the participants adopted an uncrossed-hands posture, just noticeable differences (JNDs) were lower (i.e., multisensory TOJs were more precise) when stimuli were presented from different positions, rather than from the same position. This spatial redundancy benefit was reduced when the participants adopted a crossed-hands posture, suggesting a failure to remap visuotactile space appropriately. In Experiment 2, JNDs were also lower when pairs of auditory and visual stimuli were presented from different positions, rather than from the same position. Taken together, these results demonstrate that people can use redundant spatial cues to facilitate their performance on multisensory TOJ tasks and suggest that previous studies may have systematically overestimated the precision with which people can make such judgments. These results highlight the intimate link between spatial and temporal factors in determining our perception of the multimodal objects and events in the world around us.