Purchase this article with an account.
Michael H. Herzog, Manfred Fahle; Grouping rather than orientation determines contextual modulation. Journal of Vision 2002;2(7):709. doi: 10.1167/2.7.709.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Physiological and psychophysical investigations have revealed that a context surrounding a target can strongly modulate neuronal as well as behavioral responses to that target. For high contrast targets iso-oriented contexts impair performance compared with orthogonal ones. Long or short range horizontal connections between orientation sensitive neurons are usually assumed to underly this contextual influence. However, using a recently discovered illusion, shine-through, we show psychophysically that the orientation of contextual elements does not allow predictions on contextual modulation. Hence, the effects are not based on simple interactions between orientation-sensitive horizontal connections. In the shine-through illusion, a vernier, presented for a short time, shines through a subsequently presented grating if this grating is homogeneous and extended. Otherwise the vernier remains invisible. Shine-through is also strongly diminished if single contextual lines are added above and below the grating. However, if more single lines are presented, forming a contextual grating, shine-through and good performance is regained. Therefore, the degree of contextual interference depends strongly on the overall spatial layout of the context and not on the orientation of the contextual elements per se. Grouping rather than orientation itself is the determining factor for contextual interference.
This PDF is available to Subscribers Only