ZNF804A, encoding the transcription factor zinc-finger protein 804A, is a genome-wide supported psychosis gene associated with schizophrenia and bipolar disorder. However, only little information is available on the role of ZNF804A regarding the cognitive phenotype of psychosis. In this study, we investigated the relationship between the single-nucleotide polymorphism rs1344706 (A/C, A = risk allele) in ZNF804A and attention in 200 healthy volunteers. We used the attention network test, which was designed to separate the three main components of attention (alerting, orienting and executive control). Results showed a significant association with the executive control network: the A/A genotype and the A-allele were associated with increased reaction time when conflicting information was present. In contrast, rs1344706 was not related to alerting and orienting. These results suggest that the genome-wide supported psychosis risk variant of ZNF804A is associated with altered executive control (larger conflict effect), which is a potential endophenotype of psychotic disorders.