The effect of training on preparatory attention in older adults: Evidence for the role of uncertainty in age-related preparatory deficits

Thirty-two older adults and 20 younger adults completed a simple visual detection task in which the preparatory interval (PI; 1, 3, and 5 s) that separates the warning signal from the target varied randomly on each trial. Participants were divided into two groups. In a control condition, participants completed four blocks of trials with the three PIs occur-ring equally often within a block. In the experimental condition, participants completed an equal probability block (Block 1) followed by two blocks (Blocks 2 and 3) in which the shortest PI (1 s) occurred on 2/3 of the trials, followed again by an equal probability block (Block 4). In Block 1, the results indicated a larger PI effect in older than younger participants, independent of general slowing. Increasing the likelihood of the shortest PI (Blocks 2 and 3 in the experimental condition) improved RT in older and younger adults and led to an equivalent PI effect in both age groups. This was not observed in the control condition, in which the age-related difference persisted during the four blocks of trials. Importantly, the improvement observed in the experimental group was maintained in the fourth block, where the PIs were reverted to an equal probability distribution. This supports the hypothesis that elderly participants prepare for events that have the greatest probability of occurrence and that this is a flexible process that can be modulated with brief training.