There are a number of ways of approaching this issue, none of them very satisfying. We are certainly aware of some aspects of voluntary attention—when we “pay attention” to one thing rather than another (“endogenous attention”). But much of attention is involuntary (“exogenous”). Any perceptibly sudden movement, appearance or disappearance or sound will be likely to attract exogenous attention. Subjects in perceptual experiments can try to ignore sudden movements and sounds but they attract exogenous attention nonetheless. Exogenous attention ramps up more quickly (120 ms vs 300 ms) and dies off more quickly. Eye movements can also be voluntary or involuntary. Awareness of where the eyes are pointing is a rough index of awareness of attention. There is some evidence that people are not very aware of the time and direction of their “saccades”, the quick ballistic eye movements that occur when we are visually exploring our environment. Heiner Deubel et al. showed that subjects seem to “have no explicit knowledge about their…eye position” and often don’t “notice the occurrence of even large saccadic eye movements” (1999, p. 68). However, this is not conclusive evidence that they don’t know where they are attending since they may confuse movement of attention with movements of the eyes. And the visual system could track attention even if subjects are not aware of where they are attending.
Perhaps more illumination can be achieved from work on the “landscape of attention” (Datta & DeYoe 2009). Brain imaging shows a complex rapidly shifting map of spatial attention in the visual system. Spatial attention can be “focused” at one location even though there is almost as much attention at a number of other locations and some attention throughout half the visual field. The attentional field often has a “Mexican hat” shape with amplification at the center surrounded by a ring of inhibition and then an increase outside that ring. Certainly no one is aware of all that dynamic detail though I have been unable to find any specific study addressing the issue. I think it is safe to say that in normal perception there is no phenomenology that specifies much of the detail of where one is and is not attending—nor how much one is attending. So any attempt to explain Carrasco’s results that appeals to our awareness of where we are attending takes on the burden of showing that we do have sufficiently fine-grained awareness of where we are attending.