Lateralized effects of target location on reaction times when preparing for manual aiming at a visual target

To elucidate the temporal characteristics of information processing for motor action differing in complexity in relation to both perceptual and cognitive information processing, we investigated whether the reaction times (RTs) to a visual target would be affected by task complexity (finger lifting or manual aiming), pre-cueing (with a pre-cue or without a pre-cue), or target location (five horizontal positions). Using the right hand, seven right-handed subjects performed two tasks, finger lifting and manual aiming at a target, with or without a pre-cue. The pre-cue announced the location of the target to be presented. An ANOVA showed significant interactions between task and location and between pre-cue and location with no significant interaction between task and pre-cue, indicating that the task-location interaction does not depend on whether or not a pre-cue is given. The manual-aiming RTs were longer than the finger-lifting RTs, and the effects of the target location on the RTs differed for finger lifting and manual aiming. It can be assumed that the longer RTs of manual aiming reflect the time for information processing that is needed when preparing for the aiming action per se, which is an extra movement performed in addition to the simple initiation of finger lifting. Differential RTs (DRTs) calculated by subtracting the finger-lifting RTs from the aiming RTs were therefore examined. The DRTs significantly differed for target locations (i.e., a lateralized effect), with the DRTs for an ipsilateral target appearing to be significantly shorter than those for contralateral and central targets. The lateralized effect appearing on the DRTs may be mediated by the processing of visual-spatial information about visual targets as motor preparations are made for manual aiming.     

Posture and the emergence of manual skills

In this paper, we examine how infants’ natural manual and postural activities — what they prefer and do week by week — are related to developmental transitions in reaching skill and its neuromuscular control. Using a dense, longitudinal design, we tracked the manual and postural activities of four infants in a natural, free‐play setting across the first year of life, and related these activities to two transitions in reaching as measured in a structured laboratory setting: the transition to reaching and the transition to stable reaching. Our data indicated that specific advances in the free‐play setting preceded both transitions. Head and upper torso control, the ability to extend the arm and hand to a distant target, and the ability to touch and grasp objects placed nearby were all precursors to the onset of reaching, whereas sitting independently was associated with the transition to stable reaching. We also found important individual variability in when these ‘components’ were in place, indicating that it is the ensemble of components that is essential, not the order in which they develop or the timing of their contribution. These findings suggest that subsequent experimental manipulations should be planned with respect to infants’ individual constellations of skills, rather than looking at only a single precursor to change.     

Memory for kinesthetically defined target location: evidence for manual asymmetries

Sixteen right-handed male adults performed a pointing task without vision. The participant's arm was moved passively to one of four targets which was subsequently pointed to following a delay of 1, 2, or 10 s. Our previous research on visual memory for target location showed a rapid decay which was comparable for both hands. The present study of memory for kinesthetic target location found decay for the left hand only. These findings suggest two memory stores for target location information, one visual which decays over time but is accessible to both hands and another based on kinesthetic information which is more stable and limb specific.     

The effects of endogenous attention and stimulus onsets on encoding target location

The effects of endogenously attended and non-attended stimulus onsets on spatial stimulus encoding of a target were explored in a Simon task. In each experiment participants made speeded left or right key-press responses to the colour of a target that followed a cueing display consisting of several shapes. The target appeared within some shapes and not others. The target's spatial code as measured by a Simon task was its location relative to possible target positions and relative to the centre of the display. Target location was not coded relative to the positions of onset shapes that could not contain a target. These spatial coding effects were found at cue-target intervals of 50, 300, and 1000 ms. The data indicate that target location is defined relative to the distribution of endogenous attention and reference frames aligned with the centre of the display and that the spatial code assigned to a target is not affected when attention is shifted in the target's direction.     

Posture and motion variability in non-repetitive manual materials handling tasks

In developing a motion prediction model it is important to initially consider the sources of variability that a model should reproduce. This initial step is followed by model evaluation, where the variability predicted by the model can be a useful test parameter. An existing lifting-motion dataset collected under controlled laboratory conditions was employed here to evaluate quantitatively some important sources of variability for lift motion modeling. The main source of variability was the segment being analyzed, which accounted for more than 20% of the overall variability. There was substantial left-right symmetry in individual segment variability estimates, which were largest for the upper arm segment and tended to be larger for the upper limbs than the lower limbs. Task-related factors accounted for variability mainly as a function of the segment being considered. Within-participant variability contributions to the dataset were relatively small, whereas the contribution of between-participants variability was dependent on the segment (as large as 50%) and could indicate different lifting strategies across participants. Variability was found to remain relatively constant across the different stages of the lifting movements. Implications of these results for the development and evaluation of motion prediction models are presented. Specifically, while task characteristics may be important modifiers of the mean segment trajectory during a lifting movement, their influence on variability differs based on the segment that is being considered. The relevance of the findings is discussed in terms of their utility in the ergonomic design of tasks and work spaces.     

Motor preparation of manual aiming at a visual target manipulated in size, luminance contrast, and location

We conducted two experiments to investigate whether the motor preparation of manual aiming to a visual target is affected by either the physical characteristics (size or luminance contrast) or spatial characteristics (location) of the target. Reaction time (RT) of both finger lifting (ie stimulus-detection time) and manual aiming (ie movement-triggering time) to the onset of the target was measured. The difference of RT (DRT) between two tasks (ie the difference of task complexity) was examined to clarify the temporal characteristics of manual aiming per se during visuomotor integration. Results show classical characteristics: RT decreased as either the target size or luminance contrast increased. Furthermore, the task-complexity and target-location factors significantly interacted with each other, where the aiming RT was longer than the finger-lifting RT and the effects of target location on RT differed for each task. However, the task factor did not interact with either the size or luminance-contrast factor, implying that the motor preparation of manual aiming is associated with the spatial characteristics rather than the physical characteristics of the target. Inspection of DRT revealed that the time needed for motor preparation for an ipsilateral target was significantly shorter than that for a contralateral target. This was the case both for the left and for the right hand. Foveal targets required longer processing time, implying a disadvantageous function of motor preparation for the gazed target. The left-hand superiority for the target appearing in the left visual field was also observed. Such lateralised effect and left-hand advantage to the left visual field in manual aiming suggest that visuospatial information processing is activated during the preparation of aiming action, with faster processing in the right hemisphere.     

Compatibility between stimulated eye, target location and response location

Responses to stimuli are faster when the stimulus location spatially corresponds to the required response (standard Simon effect). Recently, a similar effect has been observed with monocular stimuli. Responses were faster when the response location and the stimulated eye corresponded (monocular Simon effect). It has been suggested that distinct mechanisms may underlie these two Simon effects. Here, we attempted to study these two mechanisms simultaneously. For mean reaction time, a finding of perfect additivity was obtained. These behavioral data coupled with surface electrophysiological measures support the view that two different mechanisms contribute independently to the monocular and standard Simon effect.     

Influences of lateral preference and personality on behaviour towards a manual sorting task

Differences in task behaviour between left- and right-handers and left- and right-eared individuals have been reported (e.g.  and ) with left-handers taking longer to begin a task and right-eared individuals having a more disinhibited approach. Personality measurements are also important when examining approach behaviour. Jackson (2008) reported that those with higher neuroticism levels and a right-ear preference react faster to tasks. The current study investigated the effects of lateral preference and personality on behaviour towards a manual sorting task. Eighty-five participants completed laterality and personality scales and a card-sorting task. Degree of hand preference was found to influence behaviour towards the task with strong left-handers taking longer to begin. Those with a left congruent lateral preference (left-hand, left-ear) took significantly longer to begin the task than those with a right congruent preference. Neither neuroticism nor extraversion influenced task approach. We concluded that hand preference, and more specifically a strong left-hand preference is a good predictor of a longer initiation time on a manual task. Ear preference on its own does not predict initiation time.     

Shift of manual preference in right-handers following unimanual practice

The effect of unimanual practice of the non-preferred hand on manual asymmetry and manual preference for sequential finger movements was evaluated in right-handers before, immediately after, and 30 days following practice. The results demonstrate that unimanual practice induced a persistent shift of manual preference for the experimental task in most participants, but no significant correlation between manual asymmetry and manual preference was detected. These findings are explained by proposing that manual preference is influenced by a task-specific confidence developed from the recent history of differential use of the limbs, in interaction with a generalized confidence on a single hand for performance of motor skills.     

Detectability as a function of target location: effects of spatial configuration

Marked differences in detectability as a function of spatial location, a "detectability gradient," are observed when subjects are required to detect a briefly exposed target pattern of uncertain location in the presence of a number of nontarget patterns. Target detectability also is inversely related to the number of nontarget patterns which are present in this search paradigm. These previous findings provide strong evidence for a serial process in which increasing probability of error occurs during a scan of a rapidly degrading neural representation of the visual image following a brief exposure to the stimuli. It is not yet established whether this scan is attentional or perceptual in nature. The present experiments test the hypothesis of an attentional scan by presenting the target and nontarget patterns in spatially segregated groups. If the scan is attentional, then target detectability under these circumstances would be expected to exhibit the characteristic phenomenon of "group processing"--a close clustering of detection performance for targets located within a group and large differences in detectability across groups. As no evidence for group processing was observed, the results fail to support the view that the scan is attentional in nature but are fully consistent with a nonattentional scan.     

Exposure effects on music preference and recognition

In three experiments, the effects of exposure to melodies on their subsequent liking and recognition were explored. In each experiment, the subjects first listened to a set of familiar and unfamiliar melodies in a study phase. In the subsequent test phase, the melodies were repeated, along with a set of distractors matched in familiarity. Half the subjects were required to rate their liking of each melody, and half had to identify the melodies they had heard earlier in the study phase. Repetition of the studied melodies was found to increase liking of the unfamiliar melodies in the affect task and to be best for detection of familiar melodies in the recognition task (Experiments 1, 2, and 3). These memory effects were found to fade at different time delays between study and test in the affect and recognition tasks, with the latter leading to the most persistent effects (Experiment 2). Both study-to-test changes in melody timbre and manipulation of study tasks had a marked impact on recognition and little influence on liking judgments (Experiment 3). Thus, all manipulated variables were found to dissociate the memory effects in the two tasks. The results are consistent with the view that memory effects in the affect and recognition tasks pertain to the implicit and explicit forms of memory, respectively. Part of the results are, however, at variance with the literature on implicit and explicit memory in the auditory domain. Attribution of these differences to the use of musical material is discussed.     

Influence of target location on coincident timing performance

This study examined the influence of two stimulus-presentation methods on coincident timing performance. 50 participants performed a button press and striking task in coincidence with a target stimulus. Participants were randomly divided into either the Terminating Group, whose target light was the last in the series, or the Apparent Motion Group, whose target was not the final light in the series and allowed the apparent motion of the stimulus to continue. 20 trials at each of three velocities, 4, 8, and 12 mph, were randomly performed for each task. The analysis yielded no significant differences between groups, indicating that coincident timing performance was not dependent on the method of stimulus presentation.     

Target velocity effects on manual interception kinematics

Participants generated manual interception movements toward a target cursor that moved across a computer screen. The target reached its peak velocity either during the first third, at the midpoint, or during the last third of the movement. In Experiment 1 the view of the target was available for either the first 316, 633, 950, or 1267 ms, after which it disappeared. Results showed that for all viewing conditions, the timing of the interception velocity was related to the temporal properties of the target's trajectory. In Experiment 2, when the portion of the target trajectory that was viewed was reversed (such that participants did not see the first 316, 633, 950, or 1267 ms of the trajectory, but instead saw only the later portions of the trajectory), there was no clear relationship between the target trajectory and the timing of the aiming trajectory. These results suggest that participants use visual information early in the target's trajectory to form a representation of the target motion that is used to facilitate manual interception.     

The sensory basis of target location

Overshoot rate in a target alignment task depends on the location of the target with reference to the operational boundary of the task. Subjects performed a step tracking task under four conditions combining pursuit and compensatory display modes with joystick and crank control devices. The boundary effect was found when the joystick was used but not the crank, while the display mode had no effect, indicating that subjects moved with respect to a frame of reference based on proprioceptive information. Movements were made according to the postures adopted, irrespective of the concomitant visual consequences.     

Shape effects on memory for location

The participants were 40 students who were briefly presented 32 dot locations, one at a time, and attempted to reproduce each location after a short delay. Half of the participants completed the task with the surrounding shapes being a circle, a horizontal ellipse, and a vertical ellipse; for the other half, the surrounding shapes were a square, a triangle, and a pentagon. Elongation of the task field along an axis led to exaggerated bias along that axis, but the pattern of bias was fairly constant across the shapes. The data were modeled by assuming that bias in estimation was due to the weighting of spatial category prototypes. Modeling indicated that shape affected spacing of prototypes, but there was no evidence that it affected the number of prototypes. These results were consistent with use of a viewer-based frame of reference, with prototypes reflecting four spatial quadrants generated by left—right and up—down distinctions from the viewer’s perspective.     

Retinal location and its effect on the processing of target and distractor information

Two experiments were conducted to study the perceptual facilitation and inhibition that occurs between foveal and parafoveal or peripheral regions of the eye. Experiment 1 used a Stroop task to compare color detection latencies of foveal and parafoveal targets. The target and distractor components of the Stroop stimuli were separated and presented with varied stimulus onset asynchronies. Experiment 2 used a Stroop-like task to replicate and extend the findings into the visual periphery. Subjects were found to process foveally presented distractor information while attending to targets presented in parafoveal or peripheral regions of the eye. Distractor information that was incompatible was suppressed while compatible information was used to facilitate target processing. When the targets were presented foveally along with the distractor information, subjects appeared to automatically process the distractor information. The findings are discussed within the framework of past studies that presented subjects with competing tasks across retinal location. The implications of these findings to a two-process theory of attention are also considered.