All of the experimental results reported here should be treated as pilot study results. Our n was very small, either 1 or 2 depending on the experiment, and investigators were themselves experimental subjects. Both of these are significant limitations. Nevertheless we’re confident that any follow-up studies, with larger n, with more subjects who are not investigators, and perhaps with better equipment than we had available (for example, a camera with higher resolution), will yield results consistent with ours. We hope that any group that chooses to follow up will have an easier time than we did. To that end, we can report that post experiment both subjects’ vision returned to normal, including color discrimination (which we assessed a few days post gear), and so perhaps with verification in hand that the protocol is safe, it will be a little easier for others to get approval for use of human subjects.
The experiment as we have described it was designed to assess, among other things, phenomenal adaptation. We’ve acted so far as though what this means is obvious. But we’re now in a position to see that it isn’t obvious at all. For anyone who believes in qualia (and Dennett 1988 is right when he says that most people do, philosophers or scientists, whether they realize it or admit it or not), then the idea would be straightforward. Phenomenal adaptation would occur when, for instance, tomatoes start causing red qualia again, even if the subject is wearing the rotation gear. There are alternatives to the qualia theory. The enactive approach offers one: the idea would be that phenomenal adaptation is nothing but enactive adaptation, that is, learning new sets of sensorimotor (and related) contingencies. Our results, especially the lack of any straight-forward phenomenal adaptation, though far from decisive put at least a little pressure on the enactive view, however. Another approach (e.g., Dennett 1988) would be to first cash phenomenology out in terms of inner discriminatory states that are tied to various reactive potentials. Described in this broad way, the enactive approach would be a very special case. The reactive potentials would include behavioural dispositions and possibilities, and even predictive possibilities, but also aesthetic reactions, emotional reactions, cognitive reactions, and so forth. As Dennett puts it, the mistake made by the believer in qualia is the mistaken belief that
[…] we can isolate the qualia from everything else that is going on—at least in principle or for the sake of argument. What counts as the way the juice tastes to x can be distinguished, one supposes, from what is a mere accompaniment, contributory cause, or byproduct of this "central" way. One dimly imagines taking such cases and stripping them down gradually to the essentials, leaving their common residuum, the way things look, sound, feel, taste, smell to various individuals at various times, independently of how those individuals are stimulated or non-perceptually affected, and independently of how they are subsequently disposed to behave or believe. (1988)
On this view, JK (and to a lesser extent RG) may have been part way down the path to the only thing that would legitimately count as phenomenal adaptation, namely, changes in the way that some inner discriminatory ability is evoked and what its various consequences are. As we found, aesthetic judgments had started to adapt, and even the memory-color effect had begun to adapt in a way that speculatively may have been a reflection of alterations in what canonical colors were supposed to look like. Moreover, JK was losing his “this is weird” signals. And though we did not find evidence of semantic adaptation, it would be quite surprising, given humans’ ability to learn new languages and dialects, if after a more extended period of time semantic adaptation did not occur.
Whatever the details, for purposes of this experiment, we don’t feel compelled to take a detailed stand on any of this. We would have been satisfied with subjective report of phenomenal adaptation, and then left it to further philosophical and even psychological investigation to unpack what this could mean. Nevertheless, the adaptation to color constancy and the memory-color effect, as well as the loss of the “this is weird“ signal, are all suggestive results that we hope will help move debate in the relevant fields forward.
Acknowledgements
We would like to thank Paul Churchland for assistance in constructing the physical equipment. His job mounting the video camera and LCD goggles on the bike helmet was fantastic. We would also like to thank Eileen Cardillo and Tanya Kraljic for assistance with the Stroop experiments. We also received excellent feedback and advice from many people, including Stuart Anstis, Vilayanur Ramachanran, Pat Churchland, Paul Churchland, two referees, and many others. This work was supported by a grant form the UCSD Academic Senate. It is dedicated to the memory of Liberty Jaswal, one of the investigators who was originally intended to be the second subject, who died tragically just before we were about to begin data collection.