Long-term memory representations influence perception before edges are assigned to objects.

One way to prioritize limited mental resources for perception is to take into account the familiarity of an object to the perceiver. But does an objects' familiarity influence perception only after an object's shape has been determined, or does it influence the decision of which edges are considered part of that object? Here we compare the influence of target familiarity on whole-object masking (object-substitution masking) with its influence on edge-based masking. Two new aspects of edge-based masking are reported. First, we demonstrate that mask and target edges do not only compete (object trimming) but that mask and target edges can also cooperate (object binding), confirming that these masking effects are indeed occurring during the process of object formation and not after object shape has been determined. Second, we find that object trimming and binding are each less likely if the target is linked with a representation already present in long-term memory. Since trimming and binding effects arise very early in visual perception, these data indicate that existing long term memory representations influence the earliest stages of object assembly, before the system has even decided which edges to include in the object.