Can monkeys be trained specifically not to upshift?
We cannot at present answer this question with confidence because we have not explored it systematically. Some indirect evidence suggests that the capacity to learn to shift is limited at least. We rediscovered the fixation-upshift while trying to train monkeys to fixate in illuminated background, using shifted eye-position windows, derived from fixation in the dark. Snodderly (1987) reports having originally discovered the upshift in similar conditions. Our (and, apparently, Snodderly’s) failure to get the monkey to fixate the shifted windows may be taken to suggest that training to shift fixation is at least not generally easily possible. It is important to realize that even if monkeys would eventually turn out to be able to learn not to upshift, this result would not “explain away” the phenomenon of the fixation-upshift, which emerges spontaneously in normal conditions, as we showed in this paper. In analogy, humans can be trained to reduce the frequency of fixation-saccades (Steinm
