Synchronizing actions with events: The role of sensory information

Tasks requiring the subject to tap in synchrony to a regular sequence of stimulus events (e.g., clicks) usually elicit a response pattern in which the tap precedes the click by about 30-50 msec. This “negative asynchrony” was examined, first, by instructing subjects to use different effectors for tapping (hand vs. foot; Experiments 1 and 2), and second, by administering extrinsic auditory feedback in addition to the intrinsic tactile/kinesthetic feedback (Experiment 2). Experiment 3 controlled whether the results observed in Experiment 2 were due to purely sensory factors within the auditory modality. Results suggest that taps are synchronized with clicks at the central level by superimposing two sensory codes in time: the tactile/kinesthetic code that represents the tap (the afferent movement code) and the auditory code that represents the click (the afferent code that results from the guiding signal). Because the processing times involved in code generation are different for these two central codes, the tap has to lead over the click.     

The Lateral Coding of Rotations

A number of experimental studies have consistently shown the locus of spatial S-R compatibility effects to be the selection of the response within an abstract memory code. The purpose of the present study was to test, in the particular case of wheel rotations, the general proposition that any response that a subject internally codes in terms of left and right may be interfered with by the lateral location of the stimuli in a Simon paradigm. Experiment 1 showed that the auditory Simon effect occurred in a task where the subjects had to rotate a steering wheel bimanually either clockwise or counterclockwise according to sound pitch, despite the fact that responses of this kind are undefined with respect to laterality. Experiment 2 confirmed this result in a unimanual rotation condition and suggested that the ear-rotation compatibility effect may be added to the effect of a biomechanical factor, pronation versus supination, supporting the idea of an abstract motor code. In Experiment 3, subjects rotated the steering wheel with their hands on the lowest part of the wheel. When the response movement made the spot of a C.R.T. move laterally in accordance with the performed rotation, the subjects coded their response directly in terms of its effect on the visual display. For subjects not receiving visual feedback, no compatibility effect occurred. However, the individual data were compatible with the notion that some subjects in this group coded their responses in terms of wheel rotations, and others in terms of hand movements.     

The lateral coding of rotations: a study of the simon effect with wheel-rotation responses

A number of experimental studies have consistently shown the locus of spatial S-R compatibility effects to be the selection of the response within an abstract memory code. The purpose of the present study was to test, in the particular case of wheel rotations, the general proposition that any response that a subject internally codes in terms of left and right may be interfered with by the lateral location of the stimuli in a Simon paradigm. Experiment 1 showed that the auditory Simon effect occurred in a task where the subjects had to rotate a steering wheel bimanually either clockwise or counterclockwise according to sound pitch, despite the fact that responses of this kind are undefined with respect to laterality. Experiment 2 confirmed this result in a unimanual rotation condition and suggested that the ear-rotation compatibility effect may be added to the effect of a biomechanical factor, pronation versus supination, supporting the idea of an abstraction motor code. In Experiment 3, subjects rotated the steering wheel with their hands on the lowest part of the wheel. When the response movement made the spot of a C.R.T. move laterally in accordance with the performed rotation, the subjects coded their response directly in terms of its effect on the visual display. For subjects not receiving visual feedback, no compatibility effect occurred. however, the individual data were compatible with the notion that some subjects in this group coded their responses in terms of wheel rotations, and others in terms of hand movements.     

Response coding in the Simon task

Recent findings indicate that two distinct mechanisms can contribute to a Simon effect: a visuomotor information transmission on the one hand and a cognitive code interference on the other hand (see for e.g., Wiegand & Wascher, in Journal of Experimental Psychology: Human Perception and Performance 2005a). Furthermore, it was proposed that the occurrence of one or the other mechanism strongly depends on the way responses are coded. Visuomotor information transmission seems to depend on a correspondence between stimulus position and spatial anatomical status of the effector, whereas cognitive code interference is thought to be based on relative response location codes. To further test the spatial anatomic coding hypothesis, three experiments were conducted, in which the Simon effect with unimanual responses was investigated for horizontal (Experiment 1 and 2) and vertical (Experiment 3) stimulus-response (S-R) relations. Based on the finding of a decreasing effect function (indicating the presence of visuomotor information transmission) for horizontal and vertical S-R relations, it was concluded that visuomotor information transmission occurs whenever there is an overlap between the spatial stimulus feature and parameters of the motor representation of the response. Furthermore, the specific motor representation seems to be task dependent, that is, it entails those response parameters that clearly differentiate between the two response alternatives in a given task situation.     

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.     

Stage analysis of the reaction process using brain-evoked potentials and reaction time

Summary Motor processes partly determine reaction time (RT) in both choice reaction time and in binary classification tasks. These latter tasks are popular in cognitive psychology because the experimenter believes that he has kept the motor component simple and constant and therefore can attribute changes in RT to perceptual or cognitive processes. In this paper we used the P3 component of the event-related potential (ERP) as a time marker indicating the duration of perceptual and cognitive processes. The latency of this component is believed to reflect stimulus evaluation time independent of response selection and organization time.Two types of tasks were used: a choice-reaction time task and a binary classification task. Signal similarity and S-R compatibility additively affected RT, but only signal similarity affected P3 latency. The number of items in the positive set and response type affected both P3 latency and RT. Relative response frequency changed the bias in the cognitive evaluation of the stimulus, reflected in the latency of the P3 component, and affected RT only if the subjects preset their motor system (indexed by the late CNV). A model was presented which proposes that motor processes may partially overlap with the perceptual and cognitive evaluation of the stimulus. Both ERPs and RT are necessary tools in the study of the relative timing of these processes.     

Independent reference frames in human spatial memory: Body-centered and environmentcentered coding in near and far space

Our apparently seamless experience of the spatial environment seems to be derived from information coded across a variety of spatial reference frameworks, each tied to the metric of a different sensory or motor system. A fundamental distinction is that between body-centered and environmentcentered reference frameworks. This study reports the first clear evidence of a behavioral dissociation between body-centered and environment-centered coding in human adults. Subjects, seated in a rotating chair with closed eyes, were required to point to remembered, auditorily presented target locations. The subjects were rotated between the presentation and recall of targets. Targets were held stationary with respect to either body-centered or environment-centered spatial coordinates. Prior to recall, subjects were required to point to a series of prelearned distractor locations, which also remained fixed with reference either to the subject’s body or to the stationary environment. Memory for the target locations was selectively impaired when distractor locations were specified within the same spatial reference frame as the target, regardless of whether target and distractor locations were near to or distant from the subjects. In contrast, distractor locations specified in a different reference frame from that of the target had either little or no effect on memory for target locations.     

The influence of temporal and spatial variation on tactile identification of letters

This study was designed to show that variation in stimulation has an influence on tactile perception similar to that in the visual modality. Thirty-two subjects were required to identify Hebrew letters by the tactile sense. Identification time was found to be significantly (p less than .01) shorter when subjects could feel the letters both with temporal variation (i.e., vibrations) and spatial variation (i.e., allowing the subjects to move their fingers over the letters) than when the letters were stable. The longest identification time was found when both temporal and spatial variation were absent. The effects of the two types of tactile variation were found to be compensatory, and a possible explanation for that is offered. Possible implications of these results regarding the use of tactile perception in man-machine systems are discussed.     

Division of attention: The single-channel hypothesis revisited

Two experiments are reported in which subjects performed two forced-paced serial reaction time tasks separately and together at their maximum sustainable rates of information processing. Experiment 1 investigated the effects on the relationship between single- and dual-task performance of using tasks with the same or different input and output modality characteristics; an additional condition tested the effects on this relationship of using tasks with higher S-R compatibility. Experiment 2 investigated the effects on the relationship between single- and dual-task performance of varying information load (number of S-R alternatives). No significant differences were found in subjects' capacities to process information in single- and dual-task conditions. This finding was unaffected by: (a) the absolute information levels of the tasks, (b) whether inputs and/or outputs involved the same or different modalities, or (c) the level of S-R compatibility. The data from both experiments provide strong support for the single-channel hypothesis.     

A Simon effect for stimulus-response duration

A non-spatial variant of the Simon effect for the stimulus-response (S-R) feature of duration is reported. In Experiment 1 subjects were required to press a single response key either briefly or longer in response to the colour of a visual stimulus that varied in its presentation duration. Short keypresses were initiated faster with short than with long stimulus duration whereas the inverse was observed with long keypresses. In Experiment 2 subjects were required to press a left or right key (according to stimulus form) either briefly or longer (according to stimulus colour). The stimuli concurrently varied in their location (left or right) and duration (short or long), which were both task irrelevant. Approximately additive correspondence effects for S-R location and S-R duration were observed. To summarize, the results suggest that the irrelevant stimulus features of location and duration are processed automatically and prime corresponding responses in an independent manner.     

Persistence of the effects of choice on paired-associate learning

Four experiments are reported in which half of the subjects were permitted to choose either the stimulus or response members of S-R pairs from groupings of alternative stimuli or responses following the procedures of Perlmuter, Monty, and Kimble. The other subjects were exposed to the materials and were forced to learn the material chosen by their yoked partners. Approximately 24 h later, both groups learned PA lists comprised of either the chosen or forced material. Choosing either the stimulus or the response facilitated performance irrespective of whether the other member of the S-R pair was present at the time of choosing. This finding ruled out an associative hookup interpretation in favor of a purely motivational hypothesis and demonstrated the temporal durability of the effect of choosing.     

Cross-talk of instructed and applied arbitrary visuomotor mappings

Humans are able to perform any voluntary motor response to any environmental stimulus. This cornerstone of the flexibility of human behaviour has been investigated under the label of arbitrary visuomotor mapping. The focus of research has been the question as to how these mappings are executed once the subjects have been instructed appropriately. However, one question has been rather neglected thus far: what, in the first place, enables humans to instantaneously implement any arbitrary S-R mapping by mere instruction! We report an experiment assessing the cross-talk of arbitrary S-R mappings as a part of the instructed task representation, on the one hand, and the cross-talk of repetitively applied mappings, on the other hand. The results show a behavioural dissociation of the cross-talk elicited by instructed and applied mappings, suggesting that the first occurs on the level of task-set, whereas the latter occurs on the level of specific S-R associations.     

Transfer of orthogonal stimulus-response mappings to an orthogonal Simon task

When up-down stimulus locations are mapped to left-right keypresses, an overall advantage for the up-right/down-left mapping is often obtained that varies as a function of response eccentricity. This orthogonal stimulus-response compatibility (SRC) effect also occurs when stimulus location is irrelevant, a phenomenon called the orthogonal Simon effect, and has been attributed to correspondence of stimulus and response code polarities. The Simon effect for horizontal stimulus-response (S-R) arrangements has been shown to be affected by short-term S-R associations established through the mapping used for a prior SRC task in which stimulus location was relevant. We examined whether such associations also transfer between orthogonal SRC and Simon tasks and whether correspondence of code polarities continues to contribute to performance in the Simon task. In Experiment 1, the orthogonal Simon effect was larger after practising with an up-right/down-left mapping of visual stimuli to responses than with the alternative mapping, for which the orthogonal Simon effect tended to reverse. Experiment 2 showed similar results when practice was with high (up) and low (down) pitch tones, though the influence of practice mapping was not as large as that in Experiment 1, implying that the short-term S-R associations acquired in practice are at least in part not modality specific. In Experiment 3, response eccentricity and practice mapping were shown to have separate influences on the orthogonal Simon effect, as expected if both code polarity and acquired S-R associations contribute to performance.     

Effects of S-R and R-R compatibility on bimanual movement time

Bimanual asymmetrical movements are generally found to be slower than symmetrical movements but asymmetrical movement normally involves visual separation of targets which might account for the effect. By using a system in which the subject controls two cursors on an oscilloscope screen by moving two levers the S-R relationship on either hand can be reversed, thus providing an asymmetrical movement task without visual separation of targets. Movement times for five right-handed subjects were recorded on four unimanual and six bimanual conditions varying with respect to both S-R and R-R compatibility. In the unimanual conditions, the left hand was found to be as fast as the right when the opposite S-R relationship was used. In the bimanual tasks visual separation of targets was a relatively minor factor movement time being strongly influenced by S-R compatibility and to a lesser degree by R-R compatibility. The results suggest that compatibility, rather than being a property of a single central channel, differs, as between the two cerebral hemispheres.     

Factor Analysis,Differential Bio-Process,and Mental Organization

This study was designed to show that variation in stimulation has an influence on tactile perception similar to that in the visual modality. Thirty-two subjects were required to identify Hebrew letters by the tactile sense. Identification time was found to be significantly (p < .01) shorter when subjects could feel the letters both with temporal variation (i.e., vibrations) and spatial variation (i.e., allowing the subjects to move their fingers over the letters) than when the letters were stable. The longest identification time was found when both temporal and spatial variation were absent. The effects of the two types of tactile variation were found to be compensatory, and a possible explanation for that is offered. Possible implications of these results regarding the use of tactile perception in man-machine systems are discussed.     

Interactions Between Tactile and Proprioceptive Representations in Haptics

ABSTRACT

Neuroprosthetic limbs, regardless of their sophisticated motor control, require sensory feedback to viably interact with the environment. Toward that aim, the authors examined interrelationships between tactile and proprioceptive sensations. Through human psychophysics experiments, they evaluated error patterns of subjects estimating hand location in a horizontal 2-dimensional workspace under 3 tactile conditions. While tactile cues did not significantly affect the structure of the pattern of errors, touching the workspace reduced estimation errors. During neurophysiological experiments, a macaque grasped textured objects using 2 hand postures. Sensory coding showed dependence on both roughness of the manipulandum and posture. In summary, the authors suggest that tactile sensations underlying haptics are processed in a stable spatial reference frame provided by a proprioceptive system, and that tactile and proprioceptive inputs can be encoded simultaneously by individual cells. Such insights will be useful for providing stable, adaptive sensory feedback for neuroprosthetics.     

Inhibition of return interacts with the Simon effect: an omnibus analysis and its implications

Previous research has reported that the Simon effect (a type of stimulus-response [S-R] compatibility effect) and the inhibition of return effect (IOR; a late cuing effect) do not interact. In this brief report, we analyzed published and unpublished experiments that have examined these effects and found that IOR actually increases the Simon effect. This is a remarkable finding because most factors that delay reaction times (as IOR does) actually decrease the Simon effect. We examine this interaction within the context of seven interpretations of the effect that IOR may have on the task-irrelevant S-R code and two interpretations of the effect that IOR may have on the task-relevant S-R code, two components that underlie the Simon effect. The results falsified more than half of these interpretations, thus permitting future investigations to further reduce the number of theoretical alternatives.     

Is automatic imitation a specialized form of stimulus–response compatibility? Dissociating imitative and spatial compatibilities

In recent years research on automatic imitation has received considerable attention because it represents an experimental platform for investigating a number of interrelated theories suggesting that the perception of action automatically activates corresponding motor programs. A key debate within this research centers on whether automatic imitation is any different than other long-term S-R associations, such as spatial stimulus-response compatibility. One approach to resolving this issue is to examine whether automatic imitation shows similar response characteristics as other classes of stimulus-response compatibility. This hypothesis was tested by comparing imitative and spatial compatibility effects with a two alternative forced-choice stimulus-response compatibility paradigm. The stimulus on each trial was a left or right hand with either the index or middle finger tapping down. Speeded responses were performed with the index or middle finger of the right hand in response to the identity or the left-right spatial position of the stimulus finger. Two different tasks were administered: one that involved responding to the stimulus (S-R) and one that involved responding to the opposite stimulus (OS-R; i.e., the one not presented on that trial). Based on previous research and a connectionist model, we predicted standard compatibility effects for both spatial and imitative compatibility in the S-R task, and a reverse compatibility effect for spatial compatibility, but not for imitative compatibility, in the OS-R task. The results from the mean response times, mean percentage of errors, and response time distributions all converged to support these predictions. A second noteworthy result was that the recoding of the finger identity in the OS-R task required significantly more time than the recoding of the left-right spatial position, but the encoding time for the two stimuli in the S-R task was equivalent. In sum, this evidence suggests that the processing of spatial and imitative compatibility is dissociable with regard to two different processes in dual processing models of stimulus-response compatibility.     

汉字部件与英文字母相容性的数学模型──一种群体模板相容性的数学表达

该文运用相容性研究中的维度重叠模型以及Ｆｏｒｋ－Ｊｏｉｎ网络模型，得出群体模板的相容性定义与Ｓ－Ｒ相容性的元素匹配之间的关系式，详细讨论了汉字编码输入法研究中的学习遍数、反应时与汉字部件－英文字母相容性的关系，理论模拟与实验结果所显示的趋势符合。     

A simple method for measuring brain asymmetry in children: Application to autism

A device for measuring signal transfer within and between hemispheres has been developed at the Center for Neuropsychological Research at the University of Trier, Germany. It contains two identical panels allowing both tactile stimulation and motor response with buttons for the fingers of each hand. The buttons have two functions. They can exert a slight tactile stimulation to a finger, and they can be pressed down by the finger to provide a motor response to the tactile stimulation allowing measuring the response time. The device was used for measuring brain asymmetry in tactile processing autistic children. The participants were given a finger tapping test followed by the procedures with unilateral and bilateral processing of tactile stimulation. All participants responded positively to the test procedure and accepted it as a kind of game. The results indicated that brains were more asymmetrical in autistic children than in controls: The right hemisphere functioned quicker than the left hemisphere.