Tactile enumeration of small quantities using one hand

Our study explores various aspects of enumerating small quantities in the tactile modality. Fingertips of one hand were stimulated by a vibro-tactile apparatus (for 100/800 ms). Between 1 and 5 stimuli were presented to the right or the left hand and applied to neighboring (e.g., thumb–index–middle) or non-neighboring (e.g., thumb–middle–pinkie) fingers. The results showed a moderate increase in RT up to 4 stimuli and then a decrease for 5 stimuli. Right hand stimulation evoked more accurate performance than left hand stimulation only under short exposures (100 ms). Importantly, when the stimuli were presented to neighboring fingers, the accuracy rate was higher and the RT was faster than when presented to non-neighboring fingers. We discuss the results and suggest that when the stimuli are presented to one hand the subitizing range is 4 rather than 3. Furthermore, the right hand advantage and the efficiency for neighboring fingers are further support for the association between number and spatial arrangement of the fingers.     

Distraction and placebo: two separate routes to pain control

An explosion of recent research has studied whether placebo treatments influence health-related outcomes and their biological markers, but almost no research has examined the psychological processes required for placebo effects to occur. This study tested whether placebo treatment and cognitive distraction reduce pain through shared or independent processes. We tested the joint effects of performance of an executive working memory task and placebo treatment on thermal pain perception. An interactive effect of these two manipulations would constitute evidence for shared mechanisms, whereas additive effects would imply separate mechanisms. Participants (N = 33) reported reduced pain both when they performed the working memory task and when they received the placebo treatment, but the reductions were additive, a result indicating that the executive demands of the working memory task did not interfere with placebo analgesia. Furthermore, placebo analgesia did not impair task performance. Together, these data suggest that placebo analgesia does not depend on active redirection of attention and that expectancy and distraction can be combined to maximize pain relief.     

Choice as a Moderator of Placebo Expectation Effects: Additional Support From Two Experiments

Two experiments investigated the hypothesis that treatment choice enhances placebo treatment efficacy. In Experiment 1, prior to a pain task, participants were given either an expectation that two (inert) products could reduce pain or no expectation. In addition, participants either selected between the two products or were assigned a product to use. Participants given both the placebo expectation and treatment choice reported the lowest pain. Experiment 2 conceptually replicated this finding using a placebo paradigm with aversive auditory stimuli. Additional control conditions indicated that a choice availability (rather than choice restriction) explanation best accounted for these results.     

Localization of tactile stimuli and body parts in space: two dissociated perceptual experiences revealed by a lack of constancy in the presence of position sense and motor activity

Two motor acts were analyzed at the level of tongue and fingers. These motor acts generated illusions. When subjects voluntarily rotated the tongue by 90 degrees, the perceived orientation of a tactile stimulus applied to the tongue did not covary with the perceived orientation of the tongue itself. Analogously, when subjects voluntarily crossed two adjacent fingers, the perceived position of two tactile stimuli applied to the fingers did not covary with the perceived position of the fingers themselves. Although tongue and fingers were positioned accurately in space, a lack of perceptual constancy occurred for tactile stimuli applied to these body parts. Therefore, whereas position sense was preserved, correct localization of objects was lost. The occurrence of this perceptual dissociation suggests that spatial localization of tactile stimuli may be independent both of knowledge of body part location and motor activity.     

Perceptual learning following a long-lasting tactile reversal.

Crossing 2 adjacent fingers produces a distorted perception when 2 tactile stimuli are touched to the crossed fingertips. This is because a given pair of fingers has a functional range of action within which spatial perception is correct (uncrossed fingers) and beyond which perceived location of tactile stimuli is wrong (crossed fingers). The present study tested the possibility that this range of action could be modified following a long-lasting crossing. Therefore, the functional range of action of the 2nd and 3rd fingers was tested every month in 6 volunteers who maintained the finger crossing for as long as 6 months. The results show that after a variable period of time the range of action was enlarged such that spatial perception was correct with crossed fingers as well. The perceptual organization of the human hand therefore depends on experience and is not rigidly determined on a genetic basis.     

Processing of tactile spatial information with crossed fingers

The erroneous perception of two objects when one object is touched with crossed fingers has been explained as an inability of the brain to correctly perceive the crossed fingers' positions. This account is examined in Experiment 1, in which the perceived position of stimuli touching the crossed fingers is mapped. Crossing the third finger over the fourth displaced the perceived stimulus position counter-clockwise; crossing the third under the fourth displaced perceptions clockwise. In Experiment 2, perceived positions were found to fit a model of tactile saturation past the point of the functional range of action of the fingers. Two major conclusions are drawn: (a) Tactile stimuli are always perceived as if fingers were uncrossed, and (b) spatial mapping is present only within the functional range of finger excursion.     

疼痛恐惧对疼痛的影响及其认知机制

疼痛恐惧是把将要出现的疼痛刺激视为主要威胁而产生的一种恐惧,它会影响与疼痛相关的感知觉、注意、回避行为以及安慰剂止痛的效果.疼痛恐惧的认知模型主要有活动回避模型、恐惧-回避模型以及内感受性恐惧条件模型.未来的研究要进一步探究疼痛恐惧的认知机制,完善疼痛恐惧的认知模型并扩展疼痛恐惧的研究方法.     

Integration of hand and finger location in external spatial coordinates for tactile localization

Tactile stimulus location is automatically transformed from somatotopic into external spatial coordinates, rendering information about the location of touch in three-dimensional space. This process is referred to as tactile remapping. Whereas remapping seems to occur automatically for the hands and feet, the fingers may constitute an exception in that some studies have implied purely somatotopic coding of touch to the fingers. When participants judge the order of two tactile stimuli, they often err when the stimulated body parts (usually the two hands) are crossed, presumably because somatotopic and external coordinates are in conflict in crossed postures. Using this task, we investigated, first, whether the fingers are unlike other limbs with regard to spatial coding, by testing whether crossing effects, indicative of external coding, were observable when stimulating two fingers, either on the same or on different hands. Second, we investigated the interaction of hand and finger posture in tactile localization of finger stimuli. Crossing effects emerged when fingers and hands were crossed, suggesting external coding for all body parts. Crossing effects were larger when both hand and finger were located in the hemifield opposite to their body side, and smaller when only hand or finger lay in the opposite hemifield. We suggest that tactile location is estimated by integrating the external location of all relevant body parts, here of a finger and its belonging hand, and that such integrative coding may represent a general principle for body part processing as well as for tool use.     

Emergent equivalence relations between interoceptive (drug) and exteroceptive (visual) stimuli.

Conditional "if-then" relations between drug (interoceptive) stimuli and visual (exteroceptive) stimuli were taught to 4 normal humans. Interoceptive stimuli were the effects produced by 0.32 mg/70 kg triazolam (a prototypical benzodiazepine) and placebo (lactose-filled capsules); exteroceptive stimuli were black symbols on white flash cards. Following the training of the prerequisite conditional relations, tests of emergent relations were conducted between exteroceptive stimuli and between interoceptive and exteroceptive stimuli. Equivalence relations emerged immediately without explicit training for all 4 subjects. Accuracy of responding during the interoceptive-exteroceptive equivalence tests and subjects' self-reports showed consistent discrimination between the drug effects of triazolam and placebo. Finally, a generalization test assessed whether a novel visual stimulus presented in the context of the placebo (i.e., no drug) would generalize to visual stimuli belonging to the placebo stimulus class. All 3 subjects who completed this test reliably chose the visual stimuli belonging to the placebo class and not the visual stimuli belonging to the triazolam stimulus class. The development of equivalence relations between interoceptive and exteroceptive stimuli demonstrates that private and public stimulus events can emerge as members of the same equivalence class. Theoretical and clinical implications are discussed.     

Cognitive dissonance and the placebo response: The effect of differential justification for undergoing dummy injections

Studied the effects of cognitive dissonance on pain perception and attitudes towards injections in 48 student subjects of both sexes (average age = 20.5). In a ‘forced compliance’ design, subjects received sets of painful radiant heat stimuli, projected to their inside forearms, which they rated for painfulness and to which their GSR amplitude was recorded. During these stimuli, they ‘chose’ to receive an experimental (placebo) injection. The degree of justification for agreeing to be injected was varied. Subjects in the high-justification (HJ) condition were paid for their compliance, while subjects in the low-justification (LJ) condition were not paid. Two predictions were made from dissonance theory. The first prediction, that only LJ subjects would manifest significant post-injection analgesia when compared to subjects in a no-choice control condition, was confirmed, considering both pain ratings (p < 0.01) and GSR (p < 0.025). The second prediction, that only LJ subjects would rate injections more favourably than control subjects on a post-experimental measure, was not confirmed. The relevance of these findings to explanation of the placebo effect is discussed.     

The role of compliance in hypnotic and nonhypnotic analgesia

We modified the standard procedure for administering finger pressure pain in order to assess the extent to which subjects biased their reports of pain reduction when exposed to compliance-inducing instructions. Experiment 1 used only highly hypnotizable subjects and found that compliance-induced reductions in reported pain were about half as large as the reported reductions produced by hypnotic analgesia suggestions. Experiment 2 used low as well as high hypnotizables and administered hypnotic or nonhypnotic analgesia instructions and compliance instructions to the same subjects on separate pain trials. Reported pain reductions produced by hypnotic and nonhypnotic analgesia suggestions and those produced by compliance instructions were substantially and significantly correlated. Furthermore, hypnotizability correlated with compliance-induced reported pain reductions as highly as it correlated with the reported reductions produced by hypnotic analgesia suggestions. Among high hypnotizables (but not low hypnotizables) compliant responding was predicted by social desirability. The findings of both studies indicate that compliance strongly influences the reports of hypnotic and nonhypnotic analgesia proffered by high hypnotizables. The role of compliance in the pain reductions reported by low hypnotizables is less clear-cut.     

Reading music modifies spatial mapping in pianists

We used a novel musical Stroop task to demonstrate that musical notation is automatically processed in trained pianists. Numbers were superimposed onto musical notes, and participants played five-note sequences by mapping from numbers to fingers instead of from notes to fingers. Pianists' reaction times were significantly affected by the congruence of the note/number pairing. Nonmusicians were unaffected. In a nonmusical analogue of the task, pianists and nonmusicians showed a qualitative difference on performance of a vertical-to-horizontal stimulus-response mapping task. Pianists were faster when stimuli specifying a leftward response were presented in vertically lower locations and stimuli specifying a rightward response were presented in vertically higher locations. Nonmusicians showed the reverse pattern. No group differences were found on a task that required horizontal-to-horizontal mappings. We suggest that, as a result of learning to read and play keyboard music, pianists acquire vertical-to-horizontal visuomotor mappings that generalize outside the musical context.     

The influence of exploration mode, orientation, and configuration on the haptic Müller-Lyer illusion

We studied the impact of manner of exploration, orientation, spatial position, and configuration on the haptic Müller-Lyer illusion. Blindfolded sighted subjects felt raised-line Müller-Lyer and control stimuli. The stimuli were felt by tracing with the index finger, free exploration, grasping with the index finger and thumb, or by measuring with the use of any two or more fingers. For haptic judgments of extent a sliding tangible ruler was used. The illusion was present in all exploration conditions, with overestimation of the wings-out compared to wings-in stimuli. Tracing with the index finger reduced the magnitude of the illusion. However, tracing and grasping induced an overall underestimation of size. The illusion was greatly attenuated when stimuli were felt with the index fingers of both hands. Illusory misperception was not altered by the position in space of the Müller-Lyer stimuli. No effects of changes in the thickness of the line shaft were found, but there were effects of the length of the wing endings for the smaller, 5.1 cm stimuli. The theoretical and practical implications of the results are discussed.     

疼痛表征在自我和他人间的一致性效应

在以往研究中“pain matrix”被认为是加工自我和他人疼痛信息的特异性神经机制, 也可能是个体对他人疼痛共情的原因。但是最近的研究发现非疼痛的感觉刺激也能激活该脑区, 因此疼痛表征在自我和他人间是否存在一致性受到质疑。研究采用启动范式从两个方面入手探索自身疼痛和疼痛共情间是否存在一致性关系。实验一使用疼痛和非疼痛图片为启动刺激, 疼痛或热刺激为靶刺激, 发现相对于非疼痛图片, 疼痛图片启动下被试对自身疼痛刺激的反应时减少, 疼痛水平和情绪反应增强。实验二使用疼痛和热刺激为启动刺激, 疼痛或非疼痛图片为靶刺激, 发现相对于热刺激, 疼痛刺激启动下被试对疼痛图片的反应时减少。同时, 在两个实验中非疼痛的靶刺激都不受启动刺激的影响。这说明疼痛表征在自我和他人间存在一致性效应。     

The acquisition of task-specific productions and modifications of declarative representations in spatial-precuing tasks

The stimulus-response translation stage of human information processing plays a mediating role of relating stimuli to assigned responses. The translation stage has been implicated as the locus of a pattern of differential precuing benefits obtained in spatial-choice tasks (Proctor & Reeve, 1986; Reeve & Proctor, 1985): When pairs of finger responses from the middle and index fingers of each hand are precued, the two leftmost and two rightmost responses show the greatest benefit. This pattern of differential benefits, which occurs regardless of whether the hand placement is adjacent or overlapped, has been attributed to spatially coded representations of the stimulus and response sets in the translation stage. Experiment 1 evaluated whether the mediating role of the translation stage changes with practice. All precued pairs of responses showed equivalent benefits in the last of three sessions. This result indicates that the spatial representations used initially to translate between stimuli and responses have been altered to be more efficient or have been replaced by productions that directly specify fingers. Experiment 2 used a fourth session in which subjects were transferred from the overlapped hand placement to the adjacent placement, or vice versa. For subjects in the former condition, the pattern of differential precuing benefits reappeared in the transfer session. This lack of transfer is consistent with the hypothesis that task-specific productions develop with practice that directly relate stimuli to fingers. For subjects who practiced with the adjacent placement and switched to the overlapped placement, only a nonsignificant tendency existed for the pattern of differential precuing benefits to reappear. This failure of the pattern to reappear could indicate that spatial representations continue to be used to translate between stimuli and responses. Alternatively, as occurs with the overlapped placement, task-specific productions could be acquired that relate stimuli to fingers. If so, the failure of the pattern of differential precuing benefits to reappear would reflect a modification in the representations that are used for translation in the transfer session. Specifically, if subjects were coding the stimulus and response sets on the basis of the distinction between the two hands, as well as the spatial distinction, the differential benefits would be minimized because hand coding should benefit different responses from those benefitted by spatial coding. These alternative explanations were evaluated in Experiment 3 by having subjects who practiced with the adjacent placement switch to a placement in which the hands were crossed completely.(ABSTRACT TRUNCATED AT 400 WORDS)     

The effect of interviewer guise upon gender self-report responses as a function of interviewee's self-monitoring position

Female high and low self-monitors were interviewed by a female experimenter who adopted either an androgynous or a feminine guise. An analysis of responses scored for femininity yielded a significant interaction between self-monitoring and interviewer guise which, when subjected to further analysis, revealed a significant simple effect for high self-monitors but not for low self-monitors. High self-monitors scored significantly higher on femininity when with the feminine guise interviewer, but lower when with the androgynous guise interviewer. © 1997 John Wiley & Sons, Ltd.     

Simple movement imitation: Are kinematic features sufficient to map perceptions into actions?

The aim of this study was to pinpoint the nature of the visual features used in the automatic mapping of perceived movements into similar executed movements, following the direct matching hypothesis. In Experiment 1 subjects imitated the lifting of one of two fingers, presented with different orientations. As predicted, stimuli which were further rotated away from the posture of the executing hand elicited slower reaction times. In Experiment 2, we verified that this orientation effect was not a purely perceptual effect by presenting the same stimuli but asking subjects to respond verbally. No orientation effect was found using a verbal response. In Experiment 3, we replaced the moving fingers by two arbitrary objects moving with the trajectories of the finger tips of Experiment 1. The same orientation effect as in Experiment 1 was observed. We conclude that in this experiment participants are using purely kinematic features to map perceived into executed movements.     

Evidence of preliminary response preparation from a divided attention task

In a divided attention situation, preliminary response activations produced by stimuli on one channel were revealed through their effects on responses to stimuli on a secondary probe channel. Subjects performed concurrent but independent four-choice reaction-time tasks using the same four response fingers (middle and index fingers on both hands). In the main task, targets were large and small Ss and Ts, and medium-sized Ss and Ts sometimes appeared as distractors. Targets in the probe task were squares differing in location. A response to a probe square was faster if a distractor letter presented just before it had the same name as the target letter corresponding to that square (i.e., assigned to the same response key) than if the distractor letter had a different name--a result indicating that distractor letters cause partial response preparation. The timecourse of the effect demonstrated that preparation was based on preliminary information about distractor name that was available before distractor size had been determined. The results support models in which response preparation can sometimes begin before stimulus recognition has finished.     

Pain modulation during drives through cold and hot virtual environments.

Evidence exists that virtual worlds reduce pain perception by providing distraction. However, there is no experimental study to show that the type of world used in virtual reality (VR) distraction influences pain perception. Therefore, we investigated whether pain triggered by heat or cold stimuli is modulated by "warm "or "cold " virtual environments and whether virtual worlds reduce pain perception more than does static picture presentation. We expected that cold worlds would reduce pain perception from heat stimuli, while warm environments would reduce pain perception from cold stimuli. Additionally, both virtual worlds should reduce pain perception in general. Heat and cold pain stimuli thresholds were assessed outside VR in 48 volunteers in a balanced crossover design. Participants completed three 4-minute assessment periods: virtual "walks " through (1) a winter and (2) an autumn landscape and static exposure to (3) a neutral landscape. During each period, five heat stimuli or three cold stimuli were delivered via a thermode on the participant's arm, and affective and sensory pain perceptions were rated. Then the thermode was changed to the other arm, and the procedure was repeated with the opposite pain stimuli (heat or cold). We found that both warm and cold virtual environments reduced pain intensity and unpleasantness for heat and cold pain stimuli when compared to the control condition. Since participants wore a head-mounted display (HMD) in both the control condition and VR, we concluded that the distracting value of virtual environments is not explained solely by excluding perception of the real world. Although VR reduced pain unpleasantness, we found no difference in efficacy between the types of virtual world used for each pain stimulus.