Binary choice reaction time as a criterion of motor equivalence: Further evidence

In a previous study Heuer (1982) found shorter binary choice RTs for finger movements of the right hand when the alternative movement with the left hand was of the same form that in case of different forms. Contrary to expectation there was no corresponding effect if the fingers used were the same of different ones. This result was replicated for right hand RTs as well as left hand RTs and for male and female subjects, using a different experimental design. It is discussed in respect to different preparatory processes in the foreperiod.     

The mean fundamental frequency in stutterers and nonstutterers during reading and spontaneous speech

Corresponding to the higher tension of muscles involved in speech production, a higher mean fundamental frequency should be expected in stutterers as compared to nonstutterers. It could be shown by the change scores of the mean fundamental frequency from reading to free conversation that stutterers tend to have a higher fundamental frequency during spontaneous speech.     

The short-term storage as a buffer memory between long-term storage and the motor system: A simultaneous-processing model

It is assumed that in a free-recall task the short-term store serves as a memory buffer between the long-term store and a final motor stage of word production. Because of this the retrieval process in long-term store is not hindered by the final motor stage of word production since continued output from the long-term store queues in the buffer for motoric processing. Otherwise a time consuming communication between the two processes would be necessary. A stochastic model of this conceptualization is provided to predict the temporal course of free recall as well as a paradigm in which the contribution of the short-term store in free recall can be studied. The experimental results from this paradigm were used to test the model and to estimate short-term storage capacity on the basis of the time course of free recall. The model predictions were in good agreement with the data and the capacity estimate coincides well with estimates found by totally different methods reported in the literature.     

The role of agency for perceived ownership in the virtual hand illusion

The rubber hand illusion shows that people can perceive artificial effectors as part of their own body under suitable conditions, and the virtual hand illusion shows the same for virtual effectors. In this study, we compared a virtual version of the rubber-hand setup with a virtual-hand setup, and manipulated the synchrony between stimulation or movement of a virtual “effector” and stimulation or movement of people’s own hand, the similarity between virtual effector and people’s own hand, and the degree of agency (the degree to which the virtual effector could be controlled by people’s own movements). Synchrony-induced ownership illusion was strongly affected by agency but not similarity, which is inconsistent with top-down modulation approaches but consistent with bottom-up approaches to ownership. However, both agency and similarity induce a general bias towards perceiving an object as part of one’s body, suggesting that ownership judgments integrate various sources of information.     

Effects of motor intention on the perception of somatosensory events: A behavioural and functional magnetic resonance imaging study

The intention to execute a movement can modulate our perception of sensory events, and this modulation is observed ahead of both ocular and upper limb movements. However, theoretical accounts of these effects, and also the empirical data, are often contradictory. Accounts of “active touch”, and the premotor theory of attention, have emphasized how movement intention leads to enhanced perceptual processing at the target of a movement, or on the to-be-moved effector. By contrast, recent theories of motor control emphasize how internal “forward” model (FM) estimates may be used to cancel or attenuate sensory signals that arise as a result of self-generated movements. We used behavioural and functional brain imaging (functional magnetic resonance imaging, fMRI) to investigate how perception of a somatosensory stimulus differed according to whether it was delivered to a hand that was about to execute a reaching movement or the alternative, nonmoving, hand. The results of our study demonstrate that a somatosensory stimulus delivered to a hand that is being prepared for movement is perceived to have occurred later than when that same stimulus is delivered to a nonmoving hand. This result indicates that it takes longer for a tactile stimulus to be detected when it is delivered to a moving limb and may correspond to a change in perceptual threshold. Our behavioural results are paralleled by the results of our fMRI study that demonstrated that there were significantly reduced blood-oxygen-level-dependent (BOLD) responses within the parietal operculum and insula following somatosensory stimulation of the hand being prepared for movement, compared to when an identical stimulus was delivered to a nonmoving hand. These findings are consistent with the prediction of FM accounts of motor control that postulate that central sensory suppression of somatosensation accompanies self-generated limb movements, and with previous reports indicating that effects of sensory suppression are observed in higher order somatosensory regions.     

Effects of motor intention on the perception of somatosensory events: a behavioural and functional magnetic resonance imaging study

The intention to execute a movement can modulate our perception of sensory events, and this modulation is observed ahead of both ocular and upper limb movements. However, theoretical accounts of these effects, and also the empirical data, are often contradictory. Accounts of "active touch", and the premotor theory of attention, have emphasized how movement intention leads to enhanced perceptual processing at the target of a movement, or on the to-be-moved effector. By contrast, recent theories of motor control emphasize how internal "forward" model (FM) estimates may be used to cancel or attenuate sensory signals that arise as a result of self-generated movements. We used behavioural and functional brain imaging (functional magnetic resonance imaging, fMRI) to investigate how perception of a somatosensory stimulus differed according to whether it was delivered to a hand that was about to execute a reaching movement or the alternative, nonmoving, hand. The results of our study demonstrate that a somatosensory stimulus delivered to a hand that is being prepared for movement is perceived to have occurred later than when that same stimulus is delivered to a nonmoving hand. This result indicates that it takes longer for a tactile stimulus to be detected when it is delivered to a moving limb and may correspond to a change in perceptual threshold. Our behavioural results are paralleled by the results of our fMRI study that demonstrated that there were significantly reduced blood-oxygen-level-dependent (BOLD) responses within the parietal operculum and insula following somatosensory stimulation of the hand being prepared for movement, compared to when an identical stimulus was delivered to a nonmoving hand. These findings are consistent with the prediction of FM accounts of motor control that postulate that central sensory suppression of somatosensation accompanies self-generated limb movements, and with previous reports indicating that effects of sensory suppression are observed in higher order somatosensory regions.     

Movement-based compatibility in simple response tasks

Previous studies reported that movement observation affected movement execution. Using one and the same set of responses (i.e., lifting or tapping the finger), correspondence effects were observed for simple responses when the go-signals were similar to the responses (i.e., movies of finger movements) but not when they were dissimilar (i.e., moving squares). The difference was attributed to a higher degree of ideomotor compatibility with visible limb movements. We tried to provide further evidence for ideomotor theory by manipulating the degree to which different responses matched one and the same set of stimuli (drifting sine-wave gratings). To this end, we measured simple reaction time of dynamic (hand movements) or static (key presses) movements in response to the onset of object motion. Object motion and dynamic responses showed ideomotor compatibility without looking alike; however, both stimulus and response involved continuous displacements. Correspondence effects were observed for dynamic responses, but not for static responses.     

Hand selection for object grasping is influenced by recent motor history

Action selection processes such as those that underlie decisions about which hand to use for upcoming actions are fundamental to adaptive motor behavior. Previous research has shown that people grasp objects in ways that reflect anticipated task demands, as well as recent movement experience. However, very few studies have addressed the possible influence of recent motor history on hand selection. In the present study, participants grasped and placed objects using either their left or right hand. The results showed shorter response times to initiate successive actions when hand was repeated, even when those actions involved distinct grasp postures and object placement movements to distinct locations. Conversely, no such planning advantage was observed for repeated grasps for successive actions made with opposite hands. The findings are consistent with the idea that choices about which hand to use in the present are influenced by which hand was used in the recent past. When the same hand can be used for successive actions, planning is made more efficient, presumably because the motor parameters that specify which hand to use can be recalled from recent memory rather than formulated anew. The findings indicate that hand selection is sensitive to recent movement experience and provide novel support for computational efficiency accounts of motor history effects.     

Binary choice reaction time as a function of the relationship between durations and forms of responses

In a choice between responding with the left or right hand, some kinds of differences between the movements increase RT (Reaction Time) while others do not. Of the first kind are differences in form, while differences in the finger used are of the latter kind. In previous experiments differences in form were confounded with differences in duration. Since there is some indication that a difference in duration is sufficient to lengthen RT, both characteristics were varied separately. It turned out that a difference in form (duration being constant) has essentially the same effects as a difference in duration (form being constant): Mean RT is longer, variability of RT and MT (movement time) is larger, and frequency of choice errors is smaller than in choice between identical movements. These effects, which seem to be associated with choice between movements of different temporal patterns, are interpreted in terms of advance specification of movement parameters. Additional results on the relationship between response duration and RT suggest that RT does not depend on duration (or velocity) per se, but on how much the duration deviates from quickest performance.     

Stimulation through simulation? Motor imagery and functional reorganization in hemiplegic stroke patients

A key factor influencing reorganization of function in damaged neural networks of the adult brain is stimulation. How to stimulate motor areas of patients with paralyses is a formidable challenge. One possibility is to use internal movement simulations, or motor imagery, as an alternative to conventional therapeutic interventions that require voluntary limb movements. Before this alternative can be entertained, two preliminary issues must be resolved. First, do internal movement simulations involve the same neural circuits as comparable overt actions? Second, are motor-impaired populations capable of imagining movements they can no longer perform? Here, I show that under specific conditions, answers to these questions are affirmative. Further, I discuss preliminary evidence that internally simulating movements may induce functional reorganization of the contralesional hand representation of a chronic, densely hemiplegic, cerebral vascular accident (CVA) patient.     

Binary Choice Reaction Time as a Function of the Relationship between Durations and Forms of Responses

In a choice between responding with the left or right hand, some kinds of differences between the movements increase RT (Reaction Time) while others do not. Of the first kind are differences in form, while differences in the finger used are of the latter kind. In previous experiments differences in form were confounded with differences in duration. Since there is some indication that a difference in duration is sufficient to lengthen RT, both characteristics were varied separately. It turned out that a difference in form (duration being constant) has essentially the same effects as a difference in duration (form being constant): Mean RT is longer, variability of RT and MT (movement time) is larger, and frequency of choice errors is smaller than in choice between identical movements. These effects, which seem to be associated with choice between movements of different temporal patterns, are interpreted in terms of advance specification of movement parameters. Additional results on the relationship between response duration and RT suggest that RT does not depend on duration (or velocity) per se, but on how much the duration deviates from quickest performance.     

Human movement initiation: specification of arm, direction, and extent

This article presents a method for discovering how the defining values of forthcoming body movements are specified. In experiments using this movement precuing technique, information is given about some, none, or all of the defining values of a movement that will be required when a reaction signal is presented. It is assumed that the reaction time (RT) reflects the time to specify those values that were not precued. With RTs for the same movements in different precue conditions, it is possible to make detailed inferences about the value specification process for each of the movements under study. The present experiments were concerned with the specification of the arm, direction, and extent (or distance) of aimed hand movements. In Experiment 1 it appeared that (a) specification times during RTs were longest for arm, shorter for direction, and shortest for extent, and (b) these values were specified serially but not in an invariant order. Experiment 2 suggested that the precuing effects obtained in Experiment 1 were not attributable to stimulus identification. Experiment 3 suggested that subjects in Experiment 1 did not use precues to prepare sets of possible movements from which the required movement was later selected. The model of value specification supported by the data is consistant with a distinctive-feature view, rather than a hierarchical view, of motor programming.     

Effects of rank ordering stimuli on magnitude ratings of these and other stimuli

Five experiments investigated the effects of rank ordering stimuli on subsequent magnitude ratings of these and other stimuli. In Experiments 1 and 2, subjects first rank ordered environmental issues in terms of their importance. Ranking stimuli from “most” to “least” led to more extreme ratings than ranking them from “least” to “most,” regardless of whether the rating criterion was the same as or diametrically opposite to the ranking criterion. (For example, subjects who had previously ranked them beginning with the most important issue subsequently rated these issues not only as more important, but also as more trivial, than did subjects who had ranked them beginning with the least important.) These effects generalized to stimuli other than those that had previously been ranked, and generalized over stimulus domains. (For example, ratings of environmental issues were also affected by ranking the importance of attributes of a marriage partner.) Other experiments in the series circumscribed the conditions in which these effects occur. Results suggested that rank ordering stimuli leads subjects to adopt comparative standards, the use of which generalizes to subsequent magnitude rating tasks and produces an anchoring bias similar to that identified by A. Tversky and D. Kahneman (1974, Science (Washington, D.C.), 185, 1124–1131). Implications of these results for the cognitive processes that underlie social judgment are discussed.     

Orienting to targets by looking and pointing: Parallels and interactions in ocular and manual performance

Orienting to a target by looking and pointing is examined for parallels between the control of the two systems and interactions due to movement of the eyes and limb to the same target. Parallels appear early in orienting and may be due to common processing of spatial information for the ocular and manual systems. The eyes and limb both have shorter response latency to central visual and peripheral auditory targets. Each movement also has shorter latency and duration when the target presentation is short enough (200 msec) that no analysis of feedback of the target position is possible during the movement. Interactions appear at many stages of information processing for movement. Latency of ocular movement is much longer when the subject also points, and the eye and limb movement latencies are highly correlated for orienting to auditory targets. Final position of eyes and limb are significantly correlated only when target duration is short (200 msec). This illustrates that sensory information obtained before the movement begins is an important, but not the only, source of input about target position. Additional information that assists orienting may be passed from one system to another, since visual information gained by looking aided pointing to lights and proprioceptive information from the pointing hand seemed to assist the eyes in looking to sounds. Thus the production of this simple set of movements may be partly described by a cascade-type process of parallel analysis of spatial information for eye and hand control, but is also, later in the movement, assisted by cross-system interaction.     

Beliefs about beliefs: representation and constraining function of wrong beliefs in young children's understanding of deception

Understanding of another person's wrong belief requires explicit representation of the wrongness of this person's belief in relation to one's own knowledge. Three to nine year old children's understanding of two sketches was tested. In each sketch subjects observed how a protagonist put an object into a location x and then witnessed that in the absence of the protagonist the object was transferred from x to location y. Since this transfer came as a surprise they had to assume that the protagonist still believed that the object was in x. Subjects had to indicate where the protagonist will look for the object at his return. None of the 3–4-year old, 57% of 4–6-year old, and 86% of 6–9-year old children pointed correctly to location x in both sketches. Of the many cases where 4–6-year olds made an error they failed in only about 20% to remember the initial location correctly. As a test of the stability of children's representation of the protagonist's wrong belief the sketches continued with a statement about the protagonist's intention to either deceive an antagonist or truthfully inform a friend about the object's location. Independent of age, of those children who correctly thought that the protagonist would search in x, 85% of the time they also correctly thought that he would direct his antagonist to location y and his friend to location x. This shows that once children can represent a person's beliefs they can constrain their interpretation of this person's stated intentions to the person's beliefs. In a more story-like situation another group of children had to infer a deceptive plan from the depiction of a goal conflict between two story characters and one character's expedient utterance. At the age of 4–5 years children correctly judged this utterance as a lie only 28% of the time while 5–6-year olds did so 94% of the time. These results suggest that around the ages of 4 to 6 years the ability to represent the relationship between two or more person's epistemic states emerges and becomes firmly established.     

Performance of an unpleasant task: Effects of over- vs under-payment on perception of adequacy of rewards and task attractiveness

Subjects who came to an experiment expecting to receive a moderate amount of money for performing a task were then told, either before or after performing it, that their pay would be higher than, equal to, or less than they had expected. When the actual payment was announced after the task was performed, subjects' evaluations of the task increased with the amount they were paid; however, they estimated a higher rate of pay to be appropriate if they received either more or less than they expected than if they received what they expected. When the actual payment was announced before the task was performed (and before subjects made their decision to perform it), a different pattern emerged. Subjects rated the task more attractive when they were offered either more or less than the expected amount, while their judgments of the appropriateness of the pay offered increased with the amount of the offer. Implications of the results for incentive and dissonance theories as well as self-perception and equity theories are discussed.     

Functional between-hand differences and outflow eye position information

Pointing accuracy with an unseen hand to a just-extinguished visual target was examined in various eye movement conditions. When subjects caught the target by a saccade, they showed about the same degree of accuracy as that shown in pointing to a visible target. On the other hand, when subjects tracked a moving target by a pursuit eye movement, they systematically undershot when subsequently pointing to the target. The differential effect of the two types of eye movements on pointing tasks was examined on both the preferred and non-preferred hands, and it was found that the effect of eye movements was more prominent on the preferred hand than on the non-preferred hand. The results are discussed in relation to outflow eye position information.     

The coupling of head,reach and grasp movement in nine months old infant prehension

In 9-month-old-infants adjustments in the reaching pattern to sudden changes in object location were examined. An attractive ball was presented to the infants at their midline and on some trials (perturbation trials) the ball suddenly changed position 15 cm to the right or left during the reach. For the perturbed trials the movement times approximately doubled compared to the control trials and significantly fewer balls were grasped. The results indicate that infants need to finish the first movement before being able to redirect the reach to a new destination. The correlation between the latency of the head and hand adjustment to the perturbation were 0.85 and 0.78 for movements to the left and to the right, respectively, indicating a tight coupling. The time between the start of the perturbation and peak velocity (TPPV) was significantly shorter for the head movement than for the hand movement, indicating that the head is leading the hand.     

Sense of body and sense of action both contribute to self-recognition

Recognizing oneself, easy as it appears to be, seems at least to require awareness of one's body and one's actions. To investigate the contribution of these factors to self-recognition, we presented normal subjects with an image of both their own and the experimenter's hand. The hands could make the same, a different or no movement and could be displayed in various orientations. Subjects had to tell whether the indicated hand was theirs or not. The results showed that a congruence between visual signals and signals indicating the position of the body is one component on which self-recognition is based. Recognition of one's actions is another component. Subjects had most difficulty in recognizing their hand when movements were absent. When the two hands made different movements, subjects relied exclusively on the movement cue and recognition was almost perfect. Our findings are in line with pathological alterations in the sense of body and the sense of action.     

Choice between finger movements of different and identical form: The effect of relative signal frequency

Summary Binary choice reaction time depends on the relationship between the alternative responses. In particular, it is longer when choice is between finger movements of either hand, which have different forms, than when choice is between movements of identical form. This effect can be interpreted in terms of conjunctive preparation. If everything common to both responses is prepared in advance of the response signal, the form of the movement can only be prepared if it is the same for both responses. An alternative interpretation is in terms of single preparation. Under this hypothesis either one or the other response is prepared completely, but in case the not prepared response is demanded by the signal the time needed to shift should be longer if the movements are of different form. Thus, an effect of the form-relation will be seen only in unprepared responses, while under the hypothesis of conjunctive preparation it should be present in prepared responses as well. To decide between both hypotheses relative signal frequency and thus the proportion of expected (and prepared) responses was varied in three experiments. It turned out that the effect of the form-relation is larger with low relative signal frequency than with high frequency. This indicates the existence of single preparation. However, single preparation appears to be incomplete. When the obtained data are extrapolated to a relative signal frequency of 1.0 an effect of the form-relation still remains.This research was supported by Deutsche Forschungsgemeinschaft (grants No. He 1187/1 and 1187/2-1)