Abstract
How features of an object are bound into a unique percept is one of the puzzling problems in the cognitive and neurosciences. In order to investigate the temporal dynamics of feature binding, we used a feature fusion paradigm: a vernier (V) was immediately followed by a vernier with opposite offset direction (AntiV). Because of the very short presentation times of V and AntiV, feature fusion occurs, i.e. only one vernier is perceived. We presented various sequences of Vs and AntiVs while keeping their total physical energy (duration x luminance) constant.
Surprisingly, the contribution of each vernier to the fused percept depends not only on its energy but also on the temporal order of the elements. If, for example, a V was followed by an AntiV, the AntiV dominated the perceived offset (condition V — AntiV). This changed when the V was subdivided into two equal parts, of which one was presented before and the other after the AntiV (condition ½V — AntiV — ½V): none of the verniers dominated. In general, our results show that any level of performance can be achieved by arranging sequences of Vs and AntiVs appropriately — even though the total physical energy of V and AntiV is identical.
We conclude that for a given physical energy of V and AntiV the temporal order of presentation determines the integration of features. Different positions within the temporal sequence of events are of different importance. It seems that later elements of the sequence influence the perceived offset more than earlier ones.
Our findings provide evidence that the temporal order of elements is crucial for the integration of features. These results pose serious challenges for most models of feature processing, since they are mainly energy-based while ignoring temporal aspects.