Allen, C. & Martin, R.
Department of Psychology. Rice University. Houston, TX, USA.
Previous research has suggested that phonological short-term memory (STM) is involved when self-cueing of task switches is required. In this study, we examined whether semantic STM also plays a role in shifting. Using a predictable, cued shifting paradigm, we assessed the effect of increasing task memory load and of individual differences in both phonological and semantic STM capacity. Older adults were tested on a cued shifting paradigm under low and high memory load conditions, and in both standard and articulatory suppression (AS) conditions. For global switch costs, AS disrupted performance in the high but not the low load condition; in addition, performance in the high load condition was negatively correlated with phonological retention. For local switch costs, AS did not disrupt performance in either load condition; local switch costs showed no relation to any measure of STM capacity. In line with previous research, we hypothesize that a phonological code is used to maintain task sequence in mixed task conditions under high load conditions, and is equally involved in shift and repeat trials; in contrast, semantic STM does not play a critical role in this measure of executive function.