What is attention? What is it for? Is attention the missing link between low-level perception and cognition? If I paid more attention to writing this abstract, would people get more out of the workshop? Is my not paying more attention to writing this abstract due to a resource constraint, or other considerations which would hold even if I had a much bigger brain and dozens of hands? And how might these questions be addressed experimentally?The workshop will be roughly organized around discussion of, and experimental evidence for, various theories concerning the nature and purpose of attention, with data and models treated in that framework.
Acetylcholine, Norepinephrine, and Spatial Attention
Angela YuA rich body of experimental data indicates that the neuromodulatory systems acetylcholine (ACh) and norepinephrine (NE) are crucially involved in a variety of cognitive tasks. However, there is little consensus on their independent and joint computational functions. We present a theory in which cortical ACh and NE report different aspects of uncertainty: ACh reports expected uncertainty, coming, for instance, from known variability or ignorance about the parameters of a task, and NE signals unexpected uncertainty, as when significant aspects of the task are unpredictably changed by the experimenter (Yu & Dayan, 2002). These different sorts of uncertainty should, according to statistical learning theories, interact in a specific way to control the integration and acquisition of top-down and bottom-up information. Here, we apply these ideas to a new spatial attention task (Bentley, personal communication), which is an extension of the classical Posner Task to contextual cueing. Unlike the original Posner Task, this new spatial attention task allows the experimenter to separately manipulate expected and unexpected variations in the top-down information. In our model of the task, ACh and NE interact in a precisely specified and partly opponent, partly synergistic manner. Simulation results from the model closely replicate existent data (Phillips et al, 2000). Additional properties of ACh and NE interactions are predicted from our simulation of pharmacological manipulations: in some circumstances, for instance, the detrimental effects of lesioning one system can be partially alleviated by lesioning the other. The model also makes specific, experimentally tractable predictions regarding trial-to-trial responses of the ACh and NE neurons, as well as certain psychophysical measures such as reaction time. Experiments based on these predictions could yield insights into the workings of these neuromodulatory systems, as well as a new perspective on spatial attention.