Philosophy, Psychology and Neuroscience
Attentional Attractors and Visual Awareness
Spatial attention is often likened to a spotlight, but this metaphor is inadequate: It cannot account for the reduced sensitivity at unattended locations that accompanies facilitation at attended locations, nor for the flexibility of attention, which can be divided over several locations. Here, I will describe recent psychophysical work that systematically explored the effects of both the validity and number of peripheral attentional cues. A series of experiments demonstrated that dividing attention impairs sensitivity at the cued locations, but improves it at uncued locations. These findings are consistent with a model in which attentional cues act as attractors for spatially-tuned receptive channels: Cueing alters channels’ spatial tuning, increasing their density near a cue and decreasing it elsewhere. Multiple cues pull in different directions, reducing both of these effects. Attentional attractors thus account for these and various other findings, and offer a viable mechanism for attention’s effects. Furthermore, I will argue that they have implications for the hotly debated question of whether attention is a condition (either necessary or sufficient) for conscious experience. If attention is simply a change in the spatial tuning of retinotopic channels, then the baseline state is not inattention but rather an unbiased distribution of receptive channels. Changing the distribution of channels in retinotopic space thus constitutes attention—and in the absence of a biologically plausible scenario in which all channels are withdrawn from a specific location, it is meaningless to talk about situations in which attention is absent. Instead, I will propose that efforts should be focused on defining the causal clusters that lead to conscious perceptual experience.