Importantly, the same adapted brain state can give rise to several different perceptual aftereffects.
The mechanisms hypothesized by the model to explain different extent of aftereffect generalization (i.e., differences in sound intensities) may be tested in vivo, by comparing model predictions with results of new experiments realized ad hoc.
Nevertheless, our second finding, that same-gender aftereffects differ from different-gender aftereffects, also supports a conclusion that the effects of gender are not reducible to the psychophysical separation of male and female faces in this face space.
In particular, the model suggests that different extent of aftereffect generalization may result from different sound intensities that induce different amounts of activation in the auditory area.
The model suggests that different extent of aftereffect generalization across frequencies can be obtained by changing the intensity of the auditory stimulus that induces different amounts of activation in the auditory layer.
Moreover, also the model predicts the existence of a small interval of sound intensities that leads to largely different extent of aftereffect generalization across frequencies: no generalization is observed at sound intensity of 17; one-octave generalization occurs at 18 and 19; two-octave generalization occurs at 20; almost three-octave generalization is obtained at sound intensities above 20.
The inherent response properties of these neurons inducing weaker and narrower activation at lower sound intensities and stronger and broader activation at higher sound intensities may explain different extent of aftereffect generalization across frequencies, with no or little generalization at low sound intensities and wide generalization at high sound intensities.
By using these Hebbian rules and by changing the intensity of the auditory stimulus, different extent of aftereffect generalization across frequencies is obtained with the model, ranging from no generalization (at lower stimuli intensity) to more than two-octave generalization (at higher stimulus intensity).
The statistical results using repeated measures ANOVA showed that the initial direction was statistically different between baseline and aftereffect (F 1,21) = 53.437, p=0.0002), but no statistical difference was observed between the experiments (F 3,21) = 1.739, p=0.1897, see Figure 7E).
The underlying mechanisms of the sound-induced motion would be quite different from those of contingent aftereffects.
