Selective Attention and Action in an Artificial, Evolved Agent:
Dynamic Integration of Perception and Action
Robert Ward1 and Ronnie Ward2
(1) Centre of Cognitive Neuroscience, University of Wales, Bangor, UK
(2) Department of Computer Science, Texas A&M University
r.ward@bangor.ac.uk (Robert Ward)
We examined the selective attention abilities of a simple, artificial, evolved agent, and
considered some of the implications of the agent's performance for theories of selective
attention and action. We used a task developed by Slocum, Cowey, & Beer (2000), in which
the evolved agent was required to process two targets in an approximation of continuous time,
"catching" one target and then the other. This task requires numerous cognitive operations,
including:
1. prioritizing the first target (T1) over the second (T2);
2. selectively focusing response on T1, while preventing T2 from interfering with this
response;
3. creating a memory for the location of the unselected T2 item, so that it can be
efficiently processed later;
4. and, after catching T1, reallocating processing to focus on T2.
The evolved agent demonstrated all these abilities, and showed significant costs when
reallocating processing from T1 to T2. Detailed analysis of this "minimally cognitive agent"
suggested four implications for current psychological theories of selective processing. First,
the work demonstrates that the notion of filtering is insufficient when thinking about selective
action in an embodied, dynamic agent. Second, the model supports the idea of object-based
capacity limits: memory for T2 during T1 processing was indicative of object-based
processing where costs on a trial were incurred for processing multiple objects, not multiple
locations. Third, performance was determined by the integration of two sources, one fixed
and one flexible, similar to dual-route models of stimulus-response compatibility. The agent
therefore highlights a way to unify thinking about selective attention and stimulus-response
conflict. Finally, we show that selection of T1 was achieved by reactive inhibition of T2, so
that salient T2s were inhibited more strongly than less salient ones. Inhibition was tied to the
onset of peak conflict, as measured by constraint violation. The fact that reactive inhibition
emerges in this agent makes it likely that reactive inhibition is an important and fundamental
mechanism for selective processing in any embodied, situated, and dynamic agent.
Slocum, A.C., Downey, D.C. and Beer, R.D. (2000). Further experiments in the evolution of minimally
cognitive behavior: From perceiving affordances to selective attention. In J. Meyer, A. Berthoz, D.
Floreano, H. Roitblat and S. Wilson (Eds.), From Animals to Animats 6: Proceedings of the Sixth
International Conference on Simulation of Adaptive Behavior (pp. 430-439). MIT Press.
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