Reaction Time Asymmetries Research Articles

Reaction time asymmetries provide insight into mechanisms underlying dominant and non-dominant hand selection.

Handedness is often thought of as a hand "preference" for specific tasks or components of bimanual tasks. Nevertheless, hand selection decisions depend on many factors beyond hand dominance. While these decisions are likely influenced by which hand might show performance advantages for the particular task and conditions, there also appears to be a bias toward the dominant hand, regardless of performance advantage. This study examined the impact of hand selection decisions and workspace location on reaction time and movement quality. Twenty-six neurologically intact participants performed targeted reaching across the horizontal workspace in a 2D virtual reality environment, and we compared reaction time across two groups: those selecting which hand to use on a trial-by-trial basis (termed the choice group) and those performing the task with a preassigned hand (the no-choice group). Along with reaction time, we also compared reach performance for each group across two ipsilateral workspaces: medial and lateral. We observed a significant difference in reaction time between the hands in the choice group, regardless of workspace. In contrast, both hands showed shorter but similar reaction times and differences between the lateral and medial workspaces in the no-choice group. We conclude that the shorter reaction times of the dominant hand under choice conditions may be due to dominant hand bias in the selection process that is not dependent upon interlimb performance differences.

Quantification of gaze reaction time in infants with Pediatric Perimeter.

PurposeWe quantified the eye/head (gaze) reaction time in infants to establish a normative database for the Pediatric Perimeter device. Additionally, we tested the hypothesis that gaze reaction time will reduce with age.MethodsA cross-sectional study was conducted. Healthy infants between 3 to 10 months of age were recruited. Peripheral visual field stimuli (hemifield and quadrant stimuli) were presented in the Pediatric Perimeter device. Infant’s gaze to these stimuli was observed, documented in real time, and video recorded for offline analysis.ResultsA total of 121 infants were tested in three age group bins [3–5 months, n = 44; >5–7 months, n = 30 and >7–10 months, n = 47]. Overall, 3–5 months old had longer reaction time when compared to the older infants particularly for stimuli presented in the quadrants (Kruskal-Wallis, p<0.038). A significantly asymmetric difference (p = 0.025) in reaction time was observed between the upper (median = 820ms, IQR = 659-1093ms) and lower quadrants (median = 601ms, IQR = 540-1052ms) only for the 3–5 months old infants.ConclusionThis study provides the normative gaze reaction time of healthy infants. With increase in age, there is reduction in reaction time and disappearance of reaction time asymmetry in quadrant stimuli. The longer reaction time for upward gaze could be due to delayed maturation of neural mechanisms and/or decreased visual attention.

Is effector visibility critical for performance asymmetries in the Simon task? Evidence from hand- and foot-press responses.

The Simon effect is a stimulus-response compatibility effect in which the spatial dimension of the stimulus is task-irrelevant. This effect is often larger in reaction time (RT) for the stimulus located on the dominant-hand side of participants, for most of which it is the right hand, due to dominant-hand keypress responses being faster than non-dominant-hand responses. Experiment 1demonstrated that pedal-press responses with the left and right feet show a similar asymmetry, favoring the right response for right-footed persons. The asymmetric pattern for keypress responses was absent in results of Wallace (Journal of Experimental Psychology, 93, 163-168, 1972) when participants were not permitted to see the response keys or their hands placed on the keys at any time during the experiment, whereas we found the asymmetric pattern in a recent study when participants placed their hands on the keys prior to their being covered up. Experiments 2 and 3 showed that the Simon effect asymmetry for RT was evident even when participants were prevented from seeing the response device and their responding hands or feet. Although both hands and feet showed a Simon effect asymmetry in RT, consideration of incorrect responses suggested that whereas the asymmetry for hands is not due to a response bias, that for the feet may be due at least in part to such bias. Regardless, our results suggest that the Simon effect asymmetry is mainly an artifact of comparing conditions for which one response is made by the faster dominant right effector and the other with the slower non-dominant left effector.

Effect of Handedness and Footedness on Some Motoric Characteristics in Amateur Soccer Players

The present study aims to compare the strength of right and left legs and reaction times of soccer players depending on their hand and foot preferences. The study included 92 volunteers chosen from amateur soccer players. The measurements conducted on the subjects were anthropometric characteristics, foot reaction times (sound, light) and right and left foot squat parameters. The t-test was used for statistical procedures. Among the amateur soccer players who participated in this study, it was found that 19.57% used left hand and 67.39% used right hand as preferred. Soccer players using both hands equally were found with a rate of 13.4%. In terms of foot preference, it was found that 22.83% of the participants used left foot and 43.48% of the participants used right foot as preferred. The soccer players using both feet equally was found as 33.70%. No significant difference was found between right handers and left handers in reaction time measurements when the soccer players were grouped by hand preference. When compared with left footed players (0.29 sec), only the right foot sound reaction time of right footed players was significantly shorter (0.21 sec) at p&lt;. 05 level. Statistically significant correlation was found between soccer players’ hand and foot preference at a level of p&lt; 0.01. Left footed players had significantly higher left leg mean squat (37.19 kg) when compared with right footed players (32.27 kg). No significant difference was found between right footed (35.36 kg) and left footed (33.98) subjects in terms of mean of right leg squat. Conclusion: According to the hand preference, the proportion of those who use equally two feet increased. Reaction times and force's squat of the dominant hands and feet were better. Training programs for soccer players planned according to individual characteristics including footedness may result in performance increase and decrease in injury as a result of reduced strength and reaction time asymmetry between legs and arms.

The Motivational Power of the Happy Face

People who are cheerful have better social relationships. This might be the case because happy faces communicate an invitation to interact. Thus, happy faces might have a strong motivational effect on others. We tested this hypothesis in a set of four studies. Study 1 (N = 94) showed that approach reactions to happy faces are faster than other reactions to happy or angry faces. Study 2 (N = 99) found the same effect when comparing reactions to happy faces with reactions to disgusted faces. Supporting the notion that this effect is related to motivation, habitual social approach motivation intensified the motivational effect of happy faces (Study 3, N = 82). Finally, Study 4 (N = 40) showed that the reaction-time asymmetry does not hold for categorization tasks without approach and avoidance movements. These studies demonstrate that happy faces have a strong motivational power. They seem to activate approach reactions more strongly than angry or disgusted faces activate avoidance reactions.

Is set shifting really impaired in trait anxiety? Only when switching away from an effortfully established task set.

The current study investigated whether trait anxiety was systematically related to task-set shifting performance, using a task-switching paradigm in which 1 task was more attentionally demanding than the other. Specifically, taking advantage of a well-established phenomenon known as asymmetric switch costs, we tested the hypothesis that the association between trait anxiety and task-set shifting is most clearly observed when individuals must switch away from a more attentionally demanding task for which it was necessary to effortfully establish an appropriate task set. Ninety-one young adults completed an asymmetric switching task and trait-level mood questionnaires. Results indicated that higher levels of trait anxiety were systematically associated with greater asymmetry in reaction time (RT) switch costs. Specifically, the RT costs for switching from the more attentionally demanding task to the less demanding task were significantly greater with higher levels of trait anxiety, whereas the RT costs for switching in the opposite direction were not significantly associated with trait anxiety levels. Further analyses indicated that these associations were not attributable to comorbid dysphoria or worry. These results suggest that levels of trait anxiety may not be related to general set-shifting ability per se, but, rather, that anxiety-specific effects may primarily be restricted to when one must efficiently switch away from (or let go of) an effortfully established task set. (PsycINFO Database Record

Saccade reaction time asymmetries during task-switching in pursuit tracking.

We investigate how smooth pursuit eye movements affect the latencies of task-switching saccades. Participants had to alternate their foveal vision between a continuous pursuit task in the display center and a discrete object discrimination task in the periphery. The pursuit task was either carried out by following the target with the eyes only (ocular) or by steering an on-screen cursor with a joystick (oculomanual). We measured participants’ saccadic reaction times (SRTs) when foveal vision was shifted from the pursuit task to the discrimination task and back to the pursuit task. Our results show asymmetries in SRTs depending on the movement direction of the pursuit target: SRTs were generally shorter in the direction of pursuit. Specifically, SRTs from the pursuit target were shorter when the discrimination object appeared in the motion direction. SRTs to pursuit were shorter when the pursuit target moved away from the current fixation location. This result was independent of the type of smooth pursuit behavior that was performed by participants (ocular/oculomanual). The effects are discussed in regard to asymmetries in attention and processes that suppress saccades at the onset of pursuit.

INFLUENCE OF SIMPLE VERBAL AND NON-VERBAL STIMULI ON BRAIN ELECTRICAL ACTIVITY

In this study, the influence of analysis stimulus content on the reaction time (RT) and parameters of the brain activity was investigated. Thirty healthy right-handed volunteers (mean age 24 years) participated in the study. The dynamics of RT, characteristics of electroencephalogram (EEG) and event-related potentials (ERP) components during perception of digits and non-verbal stimuli were analyzed. The specificity of RT's asymmetry in simple and complex visual-motor reactions depended on stimulus type was revealed. The similarity of early ERP components (peak latency of 100-200 ms) for both stimuli types in simple and complex visual-motor reaction was shown. We also described the formation of specific ERP configuration for digits differentiation such as a left-sided asymmetry of component N200, and increase of peak latency of the late negative component with their extension to the parietal region.

Visuospatial asymmetry and non-spatial attention in subacute stroke patients with and without neglect

Asymmetry in performance and an association with non-lateralized attention are often mentioned as two important aspects of the clinical manifestation of visuospatial neglect. Both these aspects were investigated in 21 left (LH) and 24 right hemisphere (RH) stroke patients and in 20 healthy subjects. The letter and star cancellation subtests of the Behavioural Inattention Task (BIT) and a computerized visual reaction time task (CVRT) with stimuli presented either left, central or right in extrapersonal space were administered. In LH patients, the calculation of BIT asymmetry scores allowed a better distinction between patients with and without neglect than raw omission scores. However, in RH patients, raw and asymmetry scores led to similar classifications. In the CVRT, raw and asymmetry scores for the number of omissions also produced identical classifications. Thus, the computation of asymmetry scores for omissions did not substantially refine the diagnosis of neglect. On the other hand, more patients were classified as neglect patients by using CVRT reaction time (RT) asymmetry scores than by using BIT or CVRT omission scores. Ipsilesional RT's were chosen as a measure of general, non-lateralized attention. The ipsilesional RT's of the LH and RH patients did not differ from the healthy subjects' lateral RT's. However, within the RH group, patients with both RT asymmetries and BIT scores above cut-off level showed longer ipsilesional RT's than patients with defective RT asymmetries but normal BIT scores. This supports the idea of an interaction between lateralized and non-lateralized attentional components in neglect, in which the presence of general attentional deficits exacerbates the severity of neglect symptoms. RT tasks may contribute to the detection of asymmetries in visuospatial attention in patients with subclinical neglect symptoms, who might compensate for their lateralized deficit in paper-and-pencil tasks employing intact general attention.

EMG as a key tool to assess motor lateralization and hand reaction time asymmetries

Inconsistent and conflicting results about hand reaction time (RT) asymmetries have led to controversies over lateralization and hemispheric specialization for visuomotor transformations. In this paper, we propose a methodological solution to separate the central and peripheral processes that may be differently involved in simple visuomotor asymmetries. We provide empirical data from a simple RT task that suggests that fractionating RT into motor and premotor components with respect to a change in the electromyographic activity is necessary to disentangle motor and premotor lateralization patterns. These results call for a refinement of classical studies of visuomotor transformations using electrophysiological correlates of embedded but unrelated asymmetries rather than overt psychophysical measurements alone.

Validity of using reaction time as a basis for determining motor laterality

To the Editor: In a recent letter to the editor, [Dr. Derakhshan (2006)][1] responded to a study conducted by [Gonzalez and colleagues (2006a)][2] that explored a potential hemispheric specialization for the visual control of action independent of subject handedness. In his letter, Dr. Derakshan

Orienting visuospatial attention generates manual reaction time asymmetries in target detection and pointing

Right-handers exhibit a left hand advantage in response preparation when pointing to targets. These manual asymmetries are generally attributed to a right hemisphere specialization for spatial processing. More precisely, the left hand reaction time (RT) advantage was recently supposed to reflect specifically the right hemisphere superiority for movement planning. This study proposes to investigate a possible attentional origin for manual RT asymmetries. In a first experiment, we used the covert orienting of attention paradigm to measure subjects' RTs when reaching at targets (pointing task) both in valid, neutral and invalid conditions, either in the left or in the right visual fields and with the left and the right hand. In a second experiment, we applied the same paradigm to a detection task (key-pressing). Results revealed that orienting of attention to spatial locations was more time consuming when responding with the right than with the left hand, whether movement planning was required or not. It is suggested that the right hemisphere dominance for orienting of visuospatial attention account, partly at least, for the RT asymmetries classically observed in manual aiming.

Manual reaction time asymmetries in human subjects: the role of movement planning and attention

Hemispheric asymmetries in spatial processing are generally considered to be responsible for the shorter reaction time (RT) of the left hand classically observed for right-handers when pointing at targets. Surprisingly, despite the special role which the right cerebral hemisphere is known to play in visual attention, the attentional hypothesis for hand movement preparation asymmetries is currently rejected. This study aims to test the respective roles of visual attention and movement planning in the left hand RT advantage for goal-directed movements. Two experiments were conducted with the same subjects, a simple visual detection task and a classical pointing task, using the same lateralized stimuli. Subjects used the left hand and the right hand alternatively in order to react to the stimuli. In the detection task, the reaction consisted of simply releasing a switch as quickly as possible after the appearance of a target, whereas in the pointing task, it consisted of performing lateralized reaching movements towards the same target. The main results of this study revealed left hand shorter RTs for both tasks, emphasizing the role which right hemisphere dominance for visuospatial attention plays in manual aiming asymmetries. Moreover, a direct comparison of the RTs obtained in both experiments showed that the specific cost of movement planning was lower when using the left hand, therefore also revealing right hemisphere dominance for movement planning.

Cortical lateralization of function in rats in a visual reaction time task

Rats were trained to orient to a visual cue presented in either visual field. An asymmetry in reaction time showed that they used one eye to control responses to both visual fields. Cortical removal contralateral to this dominant eye produced a severe and permanent response deficit. Cortical removal ipsilateral to the dominant eye caused a mild and temporary change. Thus, in the rat, there is a functional lateralization that is similar to that seen in humans.

Reaction time asymmetry through bilateral versus unilateral stimulus presentation

Previous research indicates that bilateral stimulation of the visual fields results in larger asymmetry than unilateral stimulation. However, the research has largely been limited to percentage correct studies. Here, three experiments employ reaction time (RT) measures, and show that the bilateral advantage generalizes to RT, and across spatial and verbal stimulus materials (bargraphs, letters, and words). Visual field differences average about six times larger with bilateral than with unilateral presentation. Beyond promising increased power to detect hemispheric differences, the results argue against structural and attentional models of behavioral asymmetry and support a dynamic (hemispheric interaction) model.

Sex differences and cognitive/motor interference with visual half-field stimulation

This study examines the possible influence of the response on the asymmetry of lexical decision in a visual half-field study and whether sex differences in asymmetry might be determined by response factors. The results support the importance of these factors: when response demands were increased (pressing the button three times instead of once) the reaction time asymmetry was reversed for male subjects.

Hemispheric asymmetry in reaction time to color stimuli.

The simple detection of colored stimuli in the right, center, and left visual fields was examined. 10 male subjects were used in a reaction time paradigm with color (red, green, or blue), field, and hand as independent variables. A significantly faster RT to stimuli presented in the left visual field was observed, and further the left visual field-left hand combination was the fastest of all the combinations of visual-field x hand. A significant interaction of color x field suggested that red may be processed on a higher order level even in a simple detection task.

Electroencephalographic and reaction time asymmetries to musical chord stimuli

EEG was recorded over left and right hemispheres at temporal leads (T 3, T 4) referred to the vertex (Cz) in 16 right-handed male subjects. Musical chords were presented randomly in monaural sequence, during a task which required a selective motor response to stimuli presented to one ear. The integrated amplitude of the 8–13 Hz alpha rhythm was measured when subjects listened passively. Under all conditions, a lower mean alpha amplitude was recorded over the right hemisphere than the left, regardless of which ear was stimulated. Alpha suppression over the right temporal area was accentuated when the performance task directed attention to the stimulus. Reaction time to left ear stimulation was shorter than that for the right ear. With monaural stimulus presentation behavioral asymmetry, and various EEG asymmetries can be observed. There is hemispheric asymmetry associated with attention to task relevant stimuli indicated by reduction in the alpha rhythm over the right temporal area and asymmetry in reaction time with greater efficiency of the left ear to muscial chords.

Ear asymmetry in reaction time to musical sounds

Dichotic pairs of musical sounds were presented to 16 right-handed subjects, who were instructed to depress a reaction-time (RT) button when a target sound occurred in either ear. Four blocks of 36 trials were presented. During the first block, RTs to left-ear targets were significantly faster than those to right-ear targets. There were no significant ear differences during the second, third, or fourth blocks. Possible explanations for the limited duration of the left-ear advantage, and its implications for models proposed to explain the basis of RT asymmetries, are discussed.

Monaural Reaction Time Asymmetries for Speech and Non-Speech Sounds

When Ss are uncertain as to site of stimulation, they show a right ear superiority for both complex (speech) and simple (pure tone) sounds. This is true in the absence of stimulus competition and in the absence of any imposed requirement for linguistic encoding. When language encoding is required the ear preference remains the same but the efficiency of stimulus processing (speed of response) is reduced. It is concluded that there is a right ear and presumably left hemisphere advantage in auditory signal detection that is best conceptualized as due to attentional processes rather than to language dominance.