[jeffschofield]

They aren't looking at all visual illusions, they are only looking at the double-drift illusion. In the paper they say the goal of the study was to use the position shift from this particular illusion to investigate where that perceived position emerges in the processing hierarchy.

They say that the double-drift illusion reveals an integration of motion signals over a second or more, which they say makes it unlikely that early visual areas are responsible for the accumulation of position errors because they have short integration time constants.

It seems more like supporting evidence that some illusions are in the conscious domain? It would interesting to see if there have been any studies on the double-drift illusion and animals.

[treljherthj]

I get that.

But why can't we have later visual areas, but who are still at an unconscious level? From where the implication that if it's late or has long integration time is conscious?

[jeffschofield]

I might not be understanding what you mean, or I am misinterpreting the paper, or this article is just doing a poor job communicating the research. I don't believe they are assuming or implying that consciousness is required for or detected by this illusion, if that's what you mean.

The authors don't outline what their working definition of consciousness is but it seems to me that the authors are using a higher-order theory of consciousness because they refer to a conscious percept as the end result of some hierarchy of information processing. Would you agree that you consciously perceive all illusions, even if the illusions are caused by some unconscious processes (ie outside conscious domain)?

It makes sense to me that if I were investigating what a conscious percept consists of, I'd take a look at what feeds into it. They say this particular illusion has properties that make it a useful probe which they use to find evidence for WHERE in the flow from sensory representation to conscious percept this unique illusion emerges. It turns out we would not necessarily require consciousness for this illusion (that's not the claim being made), but it's still part of the neural correlates of conscious perception, hence the title of the paper: "Neural correlates of conscious visual perception lie outside the visual system: evidence from the double-drift illusion."

The long integration time in this case really only means that we are unlikely to find emergence in early visual areas, which they confirm with the first experiment that showed an illusory path doesn't share any activation patterns with a matching Gabor path (that has no internal drift) in early visual areas. Then they explored other areas with a whole-brain searchlight analysis and found a shared representation in anterior regions of the brain associated with higher-order processing. That does mean that the representation is stored outside what is usually classified as the visual system, so this evidence suggests the illusion emerges somewhere after the visual system but before the conscious percept.