Response time slowing by glucose dependent on strength of stimulus response association: investigations with the flanker task
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1
University of Surrey, United Kingdom
Previous studies showed that performance in difficult tasks, such as memory tasks, can be improved by glucose administration (Riby, 2004). Whether glucose has similar effects on sensorimotor conflicts is unclear. Here we present 2 behavioural experiments with a double-blind placebo-controlled design to investigate glucose effects on response conflicts in a flanker task. In both experiments, blood glucose levels (BCG) levels were kept around 6.5 Mmol/litre in the glucose and 5 Mmol/l in the placebo condition. In experiment 1, 12 participants (age: 25.1 years) performed an arrow version of the flanker task. Results showed that reaction times (RTs) of block 1 were 24 ms slower in the glucose (436 ms) than the placebo condition (412 ms) but not for subsequent blocks. The absence of the glucose effect in blocks 2-8 can be explained by the strong stimulus-response association (SRA) in the arrow-version of the flanker task. Experiment 2 tested this explanation by using a flanker-task version with weaker letter-key associations whereby new SRAs had to be learned after every block. Data from 12 participants (age: 20.1 years) confirmed the previous finding of slower reaction times in the glucose condition (437 ms) with an increase of 40 ms compared to the placebo condition (397 ms). Critically this effect was maintained throughout the experiment. However, the response conflict, indexed by the difference between congruent and incongruent trials, was not affected by glucose. Our data suggest that sensorimotor processes can be slowed by glucose, a finding which contrasts reports of facilitatory effects of glucose on cognition (Riby, 2004). In addition the critical variable for glucose-induced RT effects appears to be the strength of SRA rather than the actual response conflict.
Keywords:
BCG,
Information Processing
Conference:
XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011.
Presentation Type:
Poster Presentation
Topic:
Poster Sessions: Motor Information Processing
Citation:
Hope
C,
Seiss
E,
Dean
P,
Williams
K,
Guinn
A and
Sterr
A
(2011). Response time slowing by glucose dependent on strength of stimulus response association: investigations with the flanker task.
Conference Abstract:
XI International Conference on Cognitive Neuroscience (ICON XI).
doi: 10.3389/conf.fnhum.2011.207.00084
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Received:
16 Nov 2011;
Published Online:
25 Nov 2011.
*
Correspondence:
Dr. Christopher Hope, University of Surrey, Surrey, United Kingdom, c.hope@surrey.ac.uk