Abstract
[Purpose] Adult perceptual performance is heterogeneous across the visual field. Visual performance decreases with eccentricity and differs at isoeccentric locations. Performance is better along the horizontal than the vertical meridian (Horizontal-Vertical Anisotropy, HVA) and better along the lower than the upper vertical meridian (Vertical Meridian Asymmetry, VMA). Exogenous (involuntary) attention improves performance, yet preserves the shape of this performance field. These asymmetries are not present in young children. Here, we investigated whether these asymmetries are present in adolescents, and whether their performance fields are modulated by attention.
[Methods] Adults (18 to 30 years old) and adolescents (12 to 17 years old) performed a 2AFC orientation discrimination task while maintaining fixation. On each trial, Gabor patches (tilted +/- 20 deg. from vertical) simultaneously appeared at four isoeccentric locations along the vertical and horizontal meridia (6.4 deg. eccentricity). Overall task difficulty was equated across participants using a contrast threshold procedure. Attention was manipulated by presenting either one (valid) or four (neutral) peripheral pre-cues. Observers reported the orientation of the target, indicated by a response cue. Accuracy and response time were measured at each stimulus location.
[Results] As expected, in the neutral condition, adult performance showed both a pronounced HVA and VMA for accuracy and speed. In contrast, adolescent performance was similar across the 4 tested locations for accuracy and speed. Exogenous attention improved performance to the same degree at all 4 locations for both adults and adolescents.
[Conclusions] The presence of the characteristic HVA and VMA for adults and their absence for adolescents indicate that the shape of the visual performance field significantly changes from adolescence to adulthood. Moreover, exogenous attention improves performance to a similar extent across locations in both populations, preserving the shapes of their corresponding performance fields.