Abstract
Recent experimental work (e.g., Di Lollo et al., 2000) has noted that strong masking can occur even for a sparse mask (containing only four dots). In experiments where attentional focus is distributed, such a mask can produce strong effects. Recent modeling work (Francis & Hermens, 2002) showed that sparse masks and attentional focus could be modeled by weak signals generated in response to the mask. We now report additional modeling and experimental efforts that further explore this possibility. We find that although the effects of attention can be modeled as a change in the strength of the mask signal, the effect of the sparse mask seems to also be changing the properties of the target signal. We describe the significance of this finding for furthering the development of quantitative models of backward masking.