Competition with and without priority control: linking rivalry to attention through winner-take-all networks with memory.
Bottom Line: This model introduces a form of memory by forming discrete states and explains experimental data better than competitive models of rivalry without memory.This result supports the crucial role of memory in rivalry specifically and in competitive processes in general.Our approach unifies the seemingly distinct phenomena of rivalry, memory, and attention in a single model with competition as the common underlying principle.
Affiliation: Neurophysics, Philipp-University of Marburg, Marburg, Germany.Show MeSH
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Mentions: Quantitatively, we investigate blanking with respect to survival probability, the number of times a percept remerges after the blank is divided by the number of all blanks (Fig.6A). This number would be 0 if percepts perfectly alternated, 1 if there was the same percept always present, and 0.5 if alternations were random (as there is no bias to either percept in simulation nor experiment). As a consequence of the definition of dominance in simulation and the instruction to only report a percept when it was clearly dominant, a dominant percept is not always identifiable (especially for models 1 and 2) during the presentation. Hence, we also analyze switch probability as the fraction of blanks after which the other precept reemerges after a blank (Fig.6B). The difference between 1 and the sum of switch and survival probability (Fig.6C) provides the fraction of unidentifiable transitions through a blanking period. Not surprisingly, the two single WTA models (models 1 and 2) do not replicate the blanking phenomenon. Once the input decayed (cf. Fig.5B), no information about the preceding state is left, and switch and survival probability are similar (Fig.6A and B, left columns). In addition, there are many situations (up to 67.2%; Fig.6C, left columns) in which the presentation time does not allow for a clear dominant percept to emerge after a blink. In contrast, the double WTA model (model 3) replicates the increase of survival probability with increasing blanking duration (Fig.6A, third panel) and the corresponding decrease of switch probability across the blank (Fig.6B, third panel). In addition, there are fewer (up to 25.2%) presentations during which a dominant percept cannot be identified and these situations occur mainly at short blanking durations (Fig.6C). This is in line with the experimental data, where no dominant percept was reported in up to 18.8% of the total experiment time. This happened primarily at short blanking durations, possibly due to the short time between presented stimuli. The model makes an important further prediction, namely that survival probability should decrease with stronger input. Our experimental data (Fig.6, right column)—at least qualitatively—confirms this prediction.
Affiliation: Neurophysics, Philipp-University of Marburg, Marburg, Germany.