Endogenous shifts of attention cause distortions in the perception of space: Reviewing and examining the attentional repulsion effect

ABSTRACT

The functioning of spatial attention and its effects on visual processing are typically studied using chronometric and accuracy measures of behaviour. However, a growing body of literature has studied the attentional repulsion effect (ARE). Simply put, when attention is focused on one location in the visual field, stimuli appearing nearby the attended location are perceived as being located further away from the attended location than they physically are. The ARE is particularly compelling, as it is best explained by considering the receptive field properties of visual cells, thus allowing for more direct comparisons between behaviour and neural functioning. Nonetheless, most research testing the ARE has manipulated spatial attention exogenously. Furthermore, for studies that have explored endogenous attention and the ARE, empirical evidence is conflicting. Therefore, the aim of the current study was to address this inconsistency by testing the effect of voluntary attention on spatial repulsion using an optimal operationalization of endogenous attention. Centrally presented, highly informative double-cues were used to shift attention, and placeholders were included in the display to help anchor attention. Overall, we observed strong spatial repulsion effects when attention was shifted endogenously, providing compelling evidence that voluntary deployments of attention can cause perceptual distortions of space.     

Problems in Psychiatric Genetic Research: A Reply to Faraone and Biederman

This article examines evidence cited in favor of the operation of genetic factors in attention-deficit hyperactivity disorder (ADHD). Like other psychiatric conditions, a belief in the genetic basis of ADHD is derived from the results of family, twin, and adoption studies. Because family studies are widely believed to be confounded by environmental factors, primary emphasis is placed on twin and adoption studies. ADHD twin studies depend on the validity of the equal environment assumption (EEA), which holds that the environments of identical (MZ) and fraternal (DZ) twins are the same. Here it is argued that however the EEA is defined, it cannot be accepted. Therefore, the greater similarity or concordance of MZ twins when compared to DZ twins is plausibly explained by environmental factors. Adoption studies constitute a third method for investigating the role of genetic factors in ADHD. It is argued that these studies are greatly flawed by factors including non blinded diagnoses and the failure to study the biological relatives of adoptees. After an examination of the total weight of evidence in favor of a genetic basis or predisposition for ADHD, it is concluded that a role for genetic factors is not supported and that future research should be directed toward psychosocial causes