Speed of information processing and age

Abstract

Young adults and adults who were 60 yr or older were compared on measures of general intelligence, inspection time, reaction time and responding time. The intelligence test used was the Ravens Progressive Matrices and the inspection time, reaction time and responding time measures were calculated from a two choice reaction time task. Inspection time was determined by varying the duration of exposure of a stimulus prior to the onset of a mask consisting of both stimuli. Inspection time was measured as the shortest stimulus duration at which a subject could identify a stimulus with near perfect accuracy. Responding time was then measured by setting the stimulus duration at each subject's individual inspection time and then reducing the time available to make a response prior to the onset of the next stimulus. Responding time was calculated as the shortest duration of the interval between the end of a stimulus and the onset of the next stimulus at which a subject could respond with near perfect accuracy. Reaction time was measured from the onset of the stimulus to the pressing of the response key in the responding time task. Two additional measures, termed response initiation time and checking and preparation time were calculated by subtracting inspection time from reaction time and response initiation time from responding time respectively. The old subjects were found to have lower intelligence test scores, longer inspection times and longer checking and preparation times but no longer reaction times or response initiation times. These results suggest that age increases the time taken to input information correctly and to check the accuracy of the previous response and prepare for the next stimulus but that it has less effect on the time taken to initiate a response after correction identification of the stimulus.