Age-Differences in Practice Effects during Task-Switching Performance: An ERP Investigation
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1
School of Psychology, The University of Newcastle, Australia
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2
Priority Research Centre Translational Neuroscience and Mental Health Research, Australia
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3
Hunter Medical Research Institute, Australia
BACKGROUND Task-switching paradigms are used to examine age differences in cognitive control. Participants complete single task and mixed task blocks. Mixing cost refers to poorer performance on repeat trials in mixed-task blocks (mixed-repeat trials) than trials in single-task blocks (all-repeat trials). Mixing cost is believed to reflect processes required for selecting and maintaining task-sets in working memory, resolution of stimulus ambiguity, or a strategic process of incomplete disengagement of the alternative task-set on mixed-repeat trials. Switch cost results from slower and less accurate performance on switch trials than mixed-repeat trials (both from mixed-task blocks), and reflects endogenous and exogenous task-set reconfiguration processes. Increasing age produces a reliable increase in mixing cost, but inconsistent effects on switch cost. Whitson et al., (2012) showed practice contributes to such inconsistencies - where young adults use preparation time efficiently after one session of task practice, however, old adults developed efficiency in switching processes during a final test session. The aim of the current study was to examine whether practice benefits were due to improved cue or stimulus-locked processing.
METHODS 52 participants (22 young, 30 old) completed two sessions of cued task switching. We examined RT mixing and switch cost, with cue and stimulus-locked ERPs recorded from both task-switching sessions.
RESULTS We replicated larger mixing costs, and a lengthier development of efficient switching in old adults. Cue-locked waveforms showed mixing and switch positivities were present for both groups in both sessions. The mixing and switch positivities began later and were attenuated in old adults. In stimulus-locked waveforms, mixing and switch negativities were larger and prolonged in old adults across both sessions. Practice related changes in processing were restricted to reductions in the size of the switch negativity with practice.
DISCUSSION Our results suggest that reductions in stimulus interference produce practice improvements particularly in switch cost, which indicates a reduction in the difficulty associated with the bivalent stimulus for all adults. This reduction in stimulus-locked interference may indicate faster response selection and/or execution processes. Results are discussed in relation to normative theories of task-switching performance and theories of cognitive aging.
References
Whitson, L.R., Michie, P.T. & Karayanidis, F. (2012). Task practice differentially modulates task switching performance across the adult lifespan. Acta Psychologica, 139, 124 – 136.
Keywords:
cognitive control,
Aging,
Lifespan,
task-switching,
Event-related potentials
Conference:
ACNS-2013 Australasian Cognitive Neuroscience Society Conference, Clayton, Melbourne, Australia, 28 Nov - 1 Dec, 2013.
Presentation Type:
Poster
Topic:
Executive Processes
Citation:
Whitson
LR,
Karayanidis
F and
Michie
P
(2013). Age-Differences in Practice Effects during Task-Switching Performance: An ERP Investigation.
Conference Abstract:
ACNS-2013 Australasian Cognitive Neuroscience Society Conference.
doi: 10.3389/conf.fnhum.2013.212.00023
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Received:
15 Oct 2013;
Published Online:
25 Nov 2013.
*
Correspondence:
Miss. Lisa R Whitson, School of Psychology, The University of Newcastle, Newcastle, NSW, Australia, lisawhitson147@gmail.com