Lateral biases in attention and memory in neurologically healthy adults

Abstract

Attention enables us to experience the world around us and to prioritise relevant sensory information. Attentional capacity is, however, limited and the mechanisms underlying the ability to focus attention are not symmetrically presented in the brain. Healthy populations do not attend to their left and right sides equally when viewing the visual world. Some information may, therefore, be over attended while other stimuli are ignored. Pseudoneglect is the tendency to demonstrate a leftward bias in spatial attention. The strong link between attention and memory suggests that this leftward attentional bias may impact what is encoded to memory. This research study explored the impact of pseudoneglect on visual long-term memory and attention by using an eye tracker to record eye-movements. Pseudoneglect was measured using a computerised version of the line bisection task (LBT), consisting of different line lengths presented in different positions. Male and female LBT performance was also explored. Participants demonstrated a tendency to bisect lines, of different lengths more towards the left of the true midpoint. No significant gender differences with regard to LBT performance were found. The eye-tracking data produced significant differences between the number of left and right fixations according to the items viewed, F(14, 28) = 2.74 p =.01, η2 = .58, indicating a large effect size. The findings also demonstrated that more items on the left were correctly recalled when compared to the right. On average, participants recalled more items on the left (M = 66.49, SE = 1.8) than on the right (M = 61.60, SE = 2.1), t(34) = 2.86, p = .004 (one-tailed). The eta squared (.483) indicated a small to medium effect size. Although a higher number of leftward fixations were observed and more items on the left were correctly recalled, the data revealed no significant correlations between leftward biases in attention and memory. There were no significant associations between the number of fixations and the number of items recalled. The study concludes that pseudoneglect impacts attention with a higher number of fixations recorded for the left-hemifield, but no significant differences were observed concerning memory encoding.