Choice reaction time to movement of eccentric visual targets during concurrent rotary acceleration

This study investigates the influence of concurrent rotary acceleration on choice reaction time (RT) to a small, accelerating visual cursor on a cathode-ray tube. Subjects sat in an enclosed rotating device at the center of rotation and observed a 3-mm dot accelerating at different rates across a cathode-ray tube. The dot was viewed at various eccentricities under conditions of visual stimulation alone and with concurrent rotary acceleration. Subjects responded to both vertical and horizontal dot movements. There was a significant inverse relationship between choiceRT and level of dot acceleration (p< .001), and a significant direct relationship between choice RT and eccentricity (p< .001). There was no significant difference between choiceRT to vertical or horizontal dot motion (p>.25), and choiceRT was not significantly affected by concurrent rotary acceleration (p>.1Ol. The results are discussed in terms of the effects of vestibular stimulation on choiceRT to visual motion.     

Prediction of choice reaction time from information of individual stimuli

A model is developed to predict the reaction time to stimuli using information content of the individual stimuli. Review of previous research in the area showed inconsistencies due possibly to the mode of stimulus presentation or to the number of stimuli. Two experiments designed to cover the range of variables used in previous experiments were conducted. The results indicate that the model makes accurate predictions over the entire range of variables used. A comparison to earlier studies also indicates a close correspondence. nt|mis|Acknowledgment is due the Office of Naval Research which supported this research through a prime contract, NOnr 2512(00), with General Dynamics Electric Boat Division as a part of the SUBIC. (SUBmarine Integrated Control) program.     

Detection of motion onset and offset: reaction time and visual evoked potential analysis

Manual reaction time (RT) and visual evoked potentials (VEP) were measured in motion onset and offset detection tasks. A considerable homology was observed between the temporal structure of RTs and VEP intervals, provided that the change in motion was detected as soon as the VEP signal has reached critical threshold amplitude. Both manual reactions and VEP rise in latency as the velocity of the onset or offset motion decreases and were well approximated by the same negative power function with the exponent close to −2/3. This indicates that motion processing is normalised by subtracting the initial motion vector from ongoing motion. A comparison of the motion onset VEP signals in two different conditions, in one of which the observer was instructed to abstain from the reaction and in the other to indicate as fast as possible the beginning of the motion, contained accurate information about the manual response.     

Useful visual field in patients with schizophrenia: a choice reaction time study

This study examined the size of the useful visual field in patients (9 men, 6 women) with schizophrenia. A choice reaction task was conducted, and performances at 2.5, 5, 7, 10, and 25 degrees in both visual fields were measured. Three key findings were shown. First, patients had slower choice reaction times (choice RTs) than normal controls. Second, patients had slower choice RTs in the right visual field than in the left visual field. Third, patients and normal controls showed the same U-shaped choice RT pattern. The first and second findings were consistent with those of other studies. The third finding was a clear indication of the patients' performance in peripheral vision, and a comparison with normal controls suggested that there was no difference in the size of the useful visual field, at least within     

Effects of stimulus-response correspondence and verbal expectancy on choice reaction time.

The effects of S-R correspondence, verbal prediction, and stimulus discriminability were examined in a discrete, two-choice reaction-time task. Correctness of prediction and S-R correspondence were significant main effects. In addition, responses were significantly faster for correct predictions on noncorresponding trials than for incorrect predictions on corresponding trials. This latter finding indicates that an expectancy mechanism can partially offset the negative effect of spatial S-R noncorrespondence on absolute magnitude of choice reaction time.     

Assessment of sexual preference using a choice reaction time task

The purpose of this study was to investigate the use of a choice reaction time task, during which slides of sexually explicit and neutral stimuli were used as an interference task, to differentiate between groups of individuals on the basis of their sexual preference. Twenty subjects, in each of the four groups (heterosexual males, heterosexual females, homosexual males, and homosexual females), participated in this study. Sexual orientation was determined by self-report. Subjects were given a choice reaction time with interference task, followed by a recall incidental learning task. A significant higher-order interaction was found among gender, orientation, and stimulus type for all four groups. This interaction indicated a longer reaction time to slides depicting preferred sexual partners than to nonpreferred sexual partners or neutral scenes. These results indicate that sexual arousal does interfere with cognitive processing. A main effect for gender was found for the incidental learning task, with males having the fewest errors.     

Effector-specific visual information influences kinesthesis and reaction time performance in Parkinson's disease

Twelve patients diagnosed with idiopathic Parkinson's disease and 11 age-matched control participants performed a continuous bimanual wrist flexion-extension tracking task while vision of their hands was manipulated. Participants were required to match the frequency and amplitude of movements of 1 limb that was driven at 0.6 Hz by a torque motor by actively moving the contralateral limb. In half the trials, the more affected limb (subdominant for controls) was driven, and in the other half, the less affected limb (dominant for controls) was driven. Vision of both hands, vision of the driven hand only, vision of the active hand only, or no vision of the hands was allowed. Simple and probe reaction times were assessed. Parkinson's disease patients performed the tracking task to a reasonable level of temporal and spatial accuracy as compared with control participants in terms of hand phasing and root mean square error. Patients demonstrated a marked posture deviation (toward flexion), which was exaggerated when the less affected limb was active. Amplitude deviations were smaller in both groups when the less affected (dominant) limb was active and when participants had vision of the driven hand. Overall, patients delivered slower responses in both simple and probe conditions. Reaction times of Parkinson's disease patients who were allowed vision of only the active hand were longer than were those of patients in all other visual conditions, whereas visual conditions did not affect the reaction times of control participants. The authors conclude that central demands increase when movement regulation must be based solely on kinesthetic information and when vision directs attention away from the most relevant source of kinesthetic information.