Context effects on perceived position: sustained and transient temporal influences on spatial interactions

The effects of sustained and transient responses to inducing lines on the perceived position of nearby test lines were measured as constant errors in the vernier alignment of the test lines. The sustained response to the continued presence of the inducing lines had no effect on the perceived position of the test lines for very small inducing/test-line distances, and a repulsive effect for larger distances. Transient responses to the onset of the inducing lines had attractive effects for small distances, whereas transient responses to the offset of the inducing lines had repulsive effects for all distances tested. Attraction and repulsion effects on perceived position are accounted for by facilitating and inhibiting interactions that influence the relative sensitivities of an ensemble of position-selective detecting units.