Sex Differences in Decision and Movement Time

Abstract

It has been shown (Landauer, Armstrong, & Digwood, 1980) that, while there are no sex differences in visual choice reaction time, women perform faster on the decision part of the task, while men perform faster on its motor aspects. Some specialized equipment has recently been developed by Dr. G. Schuhfried Instruments of Modling, Austria. While their ERM-apparatus is primarily meant for psychopharmacological and other applied uses, the equipment divides visual reaction time into a decision component. The subject is instructed to keep the index finger of his preferred hand on a rest button. A semi-circular array of eight sensor-touch buttons are placed some 100 mm from the rest button. T h e subject is asked to respond as quickly as possible by moving his finger from the rest button and to touch the button which corresponds with the stimulus shown on a panel in the center of the appararus. The time which elapses from the presentation of the stimulus till the subject lifts his finger from the rest button is the decision time, the movement time is the time between lifting the finger from the rest position until the correct button is touched; reaction time is the sum of both values. A microprocessor controls the type of symbol presented (not only letters and numerals can be presentedn but also nonsense shapes), difficulty level of programs, repetitions, delays, etc. However, in the experiment reported, the numerals 1 to 8 were used and subjects received two blocks of 12 presentations in which six d~gi t s were shown in random order at random intervals. The first block was used for practice and the results were disregarded, while the data of the second block were used to evaluate sex differences. The equipment provides a printout of the mean decision time and mean reaction time; from this the mean movement time can be calculated. Other results provided include number of missed stimuli, wrong responses, and false alarms. A sample of 12 men and 12 women who were students or staff members of the Psychology Department was used; the subjects' mean age was 30.3 yr. (range 19 to 47 yr.) . The mean decision time for men was 810 msec. ( S D = 135) and 708 msec. ( S D = 142) for women. The difference was statistically significant: wonlen responded faster than Inen ( t = 2.19, p < .05). As far as mean movement time is concerned, men took 239 mesc. ( S D = 113) while women took 310 msec. ( S D = 8 2 ) . Again, this difference was significant ( tr , = 2.28, P < .05) . There was no significant difference in the total mean reaction times. The results confirm that women are faster in makine. a decision in a visual choice-reaction time task. This may well indicate that women have greater cognitive abilities.