Purchase this article with an account.
Peter J. Lenkic, James T. Enns; Motion Context Modulates Backward Masking of Shape. Journal of Vision 2010;10(7):974. doi: 10.1167/10.7.974.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Backward masking is the reduction in the visibility of a shape (target) when followed closely by another pattern (mask). Recent research has focused on the modulation of masking by spatial attention and gestalt influences, suggesting that backward masking occurs as a natural consequence of the object formation and updating processes that occur whenever the visual system is confronted with rapidly changing input (Enns, Lleras & Moore, 2009). Here we study how backward masking of shape is influenced by a motion sequence, comprised of visible shapes that precede and follow the masked target. On each trial, the target (34 ms shape, 34 ms blank, 34 ms mask) was preceded and followed by visible shapes (102 ms). Critically, the first and last shapes combined with the masked target to form (a) a linear motion path, (b) a curved motion path, or (c) incoherent motion. Participants discriminated between three possible masked target shapes under three different levels of mask intensity. Visual sensitivity was strongly influenced by the motion sequence, with much greater visibility when the target shape was consistent with a linear motion path than with a curved or incoherent path. Increased mask intensity also reduced target visibility more strongly for curved and incoherent paths than for linear motion. More detailed analyses will quantify the unique influence of the preceding and subsequent context shapes on target visibility. This methodology is offered as a new way to study the influence of spatial-temporal context on shape perception. Experiments are underway to extend it to speeded action tasks involving either indirect responses (i.e., key presses) or direct manual actions to the objects in motion (i.e., finger pointing).
This PDF is available to Subscribers Only