Predictive extrapolation effects can have a greater impact on visual decisions, while visual adaptation has a greater impact on conscious visual experience.

Human vision is shaped by historic and by predictive processes. The lingering impact of visual adaptation, for instance, can act to exaggerate differences between past and present inputs, whereas predictive processes can promote extrapolation effects that allow us to anticipate the near future. It is unclear to what extent either of these effects manifest in changes to conscious visual experience. It is also unclear how these influences combine, when acting in concert or opposition. We had people make decisions about the sizes of inputs, and report on levels of decisional confidence. Tests were either selectively subject to size adaptation, to an extrapolation effect, or to both of these effects. When these two effects were placed in opposition, extrapolation had a greater impact on decision making. However, our data suggest the influence of extrapolation is primarily decisional, whereas size adaptation more fully manifests in changes to conscious visual awareness.

Deep Aphantasia: a visual brain with minimal influence from priors or inhibitory feedback?

The authors are both self-described congenital aphantasics, who feel they have never been able to have volitional imagined visual experiences during their waking lives. In addition, Loren has atypical experiences of a number of visual phenomena that involve an extrapolation or integration of visual information across space. In this perspective, we describe Loren's atypical experiences of a number of visual phenomena, and we suggest these ensue because her visual experiences are not strongly shaped by inhibitory feedback or by prior expectations. We describe Loren as having Deep Aphantasia, and Derek as shallow, as for both a paucity of feedback might prevent the generation of imagined visual experiences, but for Loren this additionally seems to disrupt activity at a sufficiently early locus to cause atypical experiences of actual visual inputs. Our purpose in describing these subjective experiences is to alert others to the possibility of there being sub-classes of congenital aphantasia, one of which-Deep Aphantasia, would be characterized by atypical experiences of actual visual inputs.