触觉刺激对触觉注意启动作用的研究

目的：探讨触觉刺激对触觉注意的影响,以揭示选择性注意的机制。方法：利用在体电生理记录技术,记录了288个丘脑腹侧基底核（ventrobasal nuleus of thalamus,VB）神经元放电活动,并着重考察了不同强度触觉刺激对丘脑神经元细胞自发放电活动的影响。结果发现：触觉刺激对大部分的触觉神经元的自发放电活动均有抑制性影响。提示触觉刺激降低背景噪声可能是触发选择性触觉注意的神经机制。     

Tactile spatial sensitivity and anisotropy

A gap detection task was examined for its usefulness as a measure of tactile spatial sensitivity and as a measure of anisotropy. In Experiment 1, sensitivity was measured with a gap detection task both with and without a latex glove at three locations on the hand: the fingerpad, fingerbase, and palm. Results showed that sensitivity varied as a function of location and was correlated with changes in the density of innervation of the primary afferent fibers. In accord with other measures of spatial sensitivity, the glove had a moderate effect on sensitivity in the gap detection task. The results both with and without the glove were more similar to those obtained using another measure of spatial sensitivity, the grating orientation task, than to those obtained using the smooth-grooved task, which is considered an intensive measure. In Experiments 2-4, anisotropy was examined using the gap detection and grating orientation tasks, as well as the smooth-grooved task. Locations on the index finger, palm, and arm were tested. Results indicated that anisotropy was revealed only by tasks that relied on spatial cues. The differences between spatial sensitivity measured in the proximal-distal orientation as compared with the lateral-medial orientation varied by location and were as much as 2.35/1. The results are discussed in terms of what they may reveal about the underlying mechanisms responsible for tactile anisotropy.     

Tactile attention and the perception of moving tactile stimuli

Three experiments investigated the ability of subjects to identify the direction of movement of a pattern across the skin. In Experiments 1 and 2, subjects were required to identify the direction of movement of a pattern presented to one fingerpad while another moving pattern was being presented to an adjacent fingerpad. Subjects were instructed to attend only to the target location. The results showed that accuracy was consistently higher and reaction times were consistently faster when the two patterns moved in the same direction than when they moved in opposite directions. Both effects were largest when the two patterns were presented simultaneously. In Experiment 3, the nontarget location was the contralateral hand. In this case, performance was not affected by the presentation of the nontarget. Combined, the results suggest that movement information is processed across adjacent fingers even when subjects are explicitly instructed to attend only to one finger. Subjects do appear to be able to restrict attention to a single hand.     

Tactile Enumeration and Embodied Numerosity Among the Deaf

Representations of the fingers are embodied in our cognition and influence performance in enumeration tasks. Among deaf signers, the fingers also serve as a tool for communication in sign language. Previous studies in normal hearing (NH) participants showed effects of embodiment (i.e., embodied numerosity) on tactile enumeration using the fingers of one hand. In this research, we examined the influence of extensive visuo-manual use on tactile enumeration among the deaf. We carried out four enumeration task experiments, using 1–5 stimuli, on a profoundly deaf group (n = 16) and a matching NH group (n = 15): (a) tactile enumeration using one hand, (b) tactile enumeration using two hands, (c) visual enumeration of finger signs, and (d) visual enumeration of dots. In the tactile tasks, we found salient embodied effects in the deaf group compared to the NH group. In the visual enumeration of finger signs task, we controlled the meanings of the stimuli presentation type (e.g., finger-counting habit, fingerspelled letters, both or neither). Interestingly, when comparing fingerspelled letters to neutrals (i.e., not letters or numerical finger-counting signs), an inhibition pattern was observed among the deaf. The findings uncover the influence of rich visuo-manual experiences and language on embodied representations. In addition, we propose that these influences can partially account for the lag in mathematical competencies in the deaf compared to NH peers. Lastly, we further discuss how our findings support a contemporary model for mental numerical representations and finger-counting habits.     

Tactile localization of the direction and distance of sounds

In a previous paper, experiments were reported which demonstrated that human subjects can judge accurately the azimuthal direction of sounds using a tactile localization device. It was also demonstrated that a tactile analogue of selective auditory attention was possible with this system. Three additional experiments, reported here, indicate that subjects are also able to judge the distance of the sound source and can concurrently judge both the azimuthal direction and distance of a source. Comparisons were made between conditions where head movements were permitted lactive~ and conditions where the head was held still Ipassive, and between normal auditory judgments and tactile judgments. Active tactile performance was essentially similar to auditory performance. Active performance was superior to passive in both directional and distance judgment, but different components of the motor-sensory complex were found to contribute to active superiority in the two tasks. The implication of these experiments for the design of auditory prosthetic devices is discussed.     

触觉空间精确性与触觉神经元密度相关联的验证

本研究应用栅栏定向任务,通过对小学一年级儿童和大学生的触觉敏感性的比较,验证触觉敏感性与神经元密度的关系。结果表明：对较大的易于分辨的刺激,成人可以完成得较好,而对较细小的难于分辨的刺激,儿童成绩更好。本研究验证了高感受单元密度对应较强的触觉敏感性的假设。     

Tactile gap detection and language lateralization

Recent work suggests that hemispheric language lateralization might be related to the fine-grained temporal discriminations that are required for linguistic processing (Nicholls, 1996). Studies concerning tactile processing have also shown a significant left-hemisphere (L-H) advantage for tactile gap detection (Nicholls & Whelan, 1997). We hypothesized that language and tactile processing are both preferentially processed by the left hemisphere because it is specialized for tasks requiring fine-grained temporal resolution. Thirty-two participants (16 right and 16 left handers) were tested for both linguistic processing (using the Fused Dichotic Words Test (FDWT)) and tactile gap detection. Both right and left handers showed a significant L-H advantage for both language processing and tactile gap detection. The present study supports recent claims that language lateralization is attributable to the left hemisphere's better suitability to process tasks that require fine-grained temporal resolution.     

Tactile discrimination of competing sounds

Discriminably different sounds, concurrently presented from the left and right of the medial plane, were reduced in angular separation until subjects could no longer detect which sound was “left” and which was “right.” The procedure was repeated with hearing masked and judgments made on the basis of the tactile signals at two fingertip vibrators that received their inputs from two miniature microphones bilaterally located on the subject’s head. Auditory and tactile performance were compared under active (head movements permitted) and passive (head held still) conditions. Active and passive performance were not significantly different. Auditory and tactile performance became no better than chance at angular separations of 2.7° and 4.4°, respectively. Touch compared sufficiently well with audition to support arguments for the inclusion of sound localization information in devices which use the skin as a substitute for the ear. nt]mis|This research was conducted at the Smith-Kettlewell Institute of Visual Sciences, San Francisco, California. This institute provided the apparatus for the experiment. B. L. Richardson was on Staff Development Leave from the Applied Psychology Department of the Caulfield Institute of Technology, Melbourne, Australia.     

Tactile perception of thermal diffusivity

The thermal diffusivity of an object is a parameter that controls the rate at which heat is extracted from the hand when it touches that object. It is an important feature for distinguishing materials by means of touch. In order to quantitatively describe the ability of human observers to discriminate between materials on the basis of heat extraction rate, we conducted an experiment in which this heat extraction was performed in a controlled way. In different conditions, subjects were repeatedly asked to select from two stimuli the one that cooled faster. The discrimination threshold was around 43% of the extraction rate. A rate that was twice as slow also yielded twice the absolute threshold. When we halved the temperature difference between the beginning and end of the stimulus, the threshold did not change as much. In separate experiments, we investigated the different cues that were available in the stimulus: initial cooling rate and end temperature. Both cues were used for discrimination, but cooling rate seemed to be the most important.     

Tactile perceptual task and field dependence-independence

Differential performance with both hands by 60 normal field-dependent or field-independent subjects who were solving Nebes' test, was assessed. No difference was found between hands, but a significant difference was noted for speed of performance between field-dependent and field-independent subjects.     

Tactile selective attention and temporal masking

The presentation of a nontarget stimulus to one fingerpad interferes with the identification of a target stimulus presented to a second fingerpad. This interference has been attributed to a failure of selective attention and, more specifically, to the nontarget’s eliciting a competing response. In the present study, the temporal interval between the target and nontarget was varied to determine the extent to which a nontarget primes a competing response. The results showed more interference when the nontarget was presented after the target than when it was presented before the target. Although still consistent with a response-competition explanation, this result offered no support for a priming explanation. The function relating the amount of interference to the temporal separation between the target and nontarget was similar to the functions obtained in studies of temporal masking, and this prompted a second experiment in which temporal masking was examined. These results, obtained with stimuli presented to the same fingerpad, indicate that response competition may be a major factor in temporal masking and that similar processes are involved in temporal masking and selective attention.     

Art Media and the Sense Modalities: Tactile Pictures

It is widely assumed that the art media can be individuated with reference to the sense modalities. Different art media are perceived by means of different sense modalities, and this tells us what properties of each medium are aesthetically relevant. The case of pictures appears to fit this principle well, for pictures are deemed purely and paradigmatically visual representations. However, recent psychological studies show that congenitally and early blind people have the ability to interpret and make raised-line drawings through touch. This shows that pictures are not essentially visual representations. The view that pictures are essentially visual follows from influential views of the nature of depiction and of the nature of vision that are mistaken. By rooting out the mistake, we learn something about pictures, something about vision, and something about the doctrine that art media are individuated by the sense modalities.     

Tactile retention: Reading with the skin

In four experiments, subjects were required to identify sequences of random digits, letters, or words drawn on the skin. The passive tactile digit span was determined to be three items when the digits were drawn with an interstimulus interval of 1 sec. Identification was significantly better for words than for random letter sequences. Slower rates of presentation produced better tactile retention. The deficiencies in passive retention were ascribed to two processes, the generation of aftersensations and a difficulty in the generation of a unitary percept. Perceptual activity may normally act to inhibit aftersensations and facilitate the construction of a unitary percept The results supported the notion that the tactile span of immediate memory is labile and may be limited by passivity.     

The Fabric of Thought: Priming Tactile Properties During Reading Influences Direct Tactile Perception

The present studies examined whether implied tactile properties during language comprehension influence subsequent direct tactile perception, and the specificity of any such effects. Participants read sentences that implicitly conveyed information regarding tactile properties (e.g., Grace tried on a pair of thick corduroy pants while shopping) that were either related or unrelated to fabrics and varied in implied texture (smooth, medium, rough). After reading each sentence, participants then performed an unrelated rating task during which they felt and rated the texture of a presented fabric. Results demonstrated that the texture properties implied in sentences influence direct tactile perception. Specifically, after reading about a smooth or rough texture, subsequent fabric ratings became notably smoother or rougher, respectively. However, we also show that there was some specificity to these effects: Fabric‐related sentences elicited more specific and interactive effects on subsequent ratings. Together, we demonstrate that under certain circumstances, language comprehension can prime tactile representations and affect direct tactile perception. Results are discussed with regard to the nature and scope of multimodal mental simulation during reading.     

Tactile "capture" of audition

Previous research has demonstrated that the localization of auditory or tactile stimuli can be biased by the simultaneous presentation of a visual stimulus from a different spatial position. We investigated whether auditory localization judgments could also be affected by the presentation of spatially displaced tactile stimuli, using a procedure designed to reveal perceptual interactions across modalities. Participants made left-right discrimination responses regarding the perceived location of sounds, which were presented either in isolation or together with tactile stimulation to the fingertips. The results demonstrate that the apparent location of a sound can be biased toward tactile stimulation when it is synchronous, but not when it is asynchronous, with the auditory event. Directing attention to the tactile modality did not increase the bias of sound localization toward synchronous tactile stimulation. These results provide the first demonstration of the tactile capture of audition.