TY - JOUR

T1 - Effects of caffeine on reaction time are mediated by attentional rather than motor processes

AU - Saville, Christopher W. N.

AU - de Morree, H M

AU - Dundon, Neil M

AU - Marcora, S M

AU - Klein, Christroph

PY - 2018/3

Y1 - 2018/3

N2 - BACKGROUND: Caffeine has a well-established effect on reaction times (RTs) but the neurocognitive mechanisms underlying this are unclear.METHODS: In the present study, 15 female participants performed an oddball task after ingesting caffeine or a placebo, and electroencephalographic data were obtained. Single-trial P3b latencies locked to the stimulus and to the response were extracted and mediation models were fitted to the data to test whether caffeine's effect on RTs was mediated by its effect on either type of P3b latencies.RESULTS: Stimulus-locked latencies showed clear evidence of mediation, with approximately a third of the effect of caffeine on RTs running through the processes measured by stimulus-locked latencies. Caffeine did not affect response-locked latencies, so could not mediate the effect.DISCUSSION: These findings are consistent with caffeine's effect on RTs being a result of its effect on perceptual-attentional processes, rather than motor processes. The study is the first to apply mediation analysis to single-trial P3b data and this technique holds promise for mental chronometric studies into the effects of psychopharmacological agents. The R code for performing the single trial analysis and mediation analysis are included as supplementary materials.

AB - BACKGROUND: Caffeine has a well-established effect on reaction times (RTs) but the neurocognitive mechanisms underlying this are unclear.METHODS: In the present study, 15 female participants performed an oddball task after ingesting caffeine or a placebo, and electroencephalographic data were obtained. Single-trial P3b latencies locked to the stimulus and to the response were extracted and mediation models were fitted to the data to test whether caffeine's effect on RTs was mediated by its effect on either type of P3b latencies.RESULTS: Stimulus-locked latencies showed clear evidence of mediation, with approximately a third of the effect of caffeine on RTs running through the processes measured by stimulus-locked latencies. Caffeine did not affect response-locked latencies, so could not mediate the effect.DISCUSSION: These findings are consistent with caffeine's effect on RTs being a result of its effect on perceptual-attentional processes, rather than motor processes. The study is the first to apply mediation analysis to single-trial P3b data and this technique holds promise for mental chronometric studies into the effects of psychopharmacological agents. The R code for performing the single trial analysis and mediation analysis are included as supplementary materials.

KW - Journal Article

KW - Cafeine

KW - Single trial analysis

KW - Mediation

KW - Event-related potentials (ERP)

KW - Reaction times

KW - P300

U2 - 10.1007/s00213-017-4790-7

DO - 10.1007/s00213-017-4790-7

M3 - Article

C2 - 29273820

VL - 235

SP - 749

EP - 759

JO - Psychopharmacology

JF - Psychopharmacology

SN - 0033-3158

IS - 3

ER -