Genetically mediated resistance to distraction: Influence of dopamine transporter genotype on attentional selection

• ¹ Monash University, School of Psychological Sciences, Australia
• ² Monash University, School of Psychological Sciences, Australia
• ³ The University of Queensland, School of Psychology, Australia
• ⁴ The University of Queensland, Australia
• ⁵ The University of Queensland, Queensland Brain Institute (QBI), Australia
• ⁶ Cardiff University, School of Psychology, United Kingdom

Although lateral differences, or asymmetries, in spatial attention have been linked to inter-hemispheric differences in dopamine signaling, it remains unclear whether such effects are primarily motoric or attentional in nature. Here we took a cognitive genetic approach to adjudicate between roles for dopamine in attentional versus response selection. A sample of non-clinical adults (N=518) performed three cognitive tasks (attentional competition, spatial cuing and flanker tasks) that varied in the degree to which they required participants to resolve attentional competition or response competition. All participants were genotyped for functional tandem repeat polymorphisms of the dopamine transporter gene (DAT1; SLC6A3) which influence the level of available synaptic dopamine and confer risk to disorders of inattention. DAT1 genotype modulated the effects of the irrelevant stimuli during the spatial competition but not the spatial cuing and flanker tasks. Specifically, compared to individuals who were heterozygous or homozygous for the 10-repeat allele of a tandem repeat polymorphism, individuals without this allele demonstrated a remarkable immunity to distraction in the left hemifield, such that response times were unaffected by increases in the number of distractor stimuli when they were presented to the left hemi-field. All three genotype groups exhibited uniform costs of resolving leftward response selection in a standard flanker task. The key effect could be explained by speed/accuracy trade-offs and therefore suggest that participants without the 10 repeat allele of the DAT1 tandem repeat polymorphism possess an enhanced attentional ability to suppress task-irrelevant stimuli in the left hemifield.