Many adaptive capabilities of the visual system are well known and are usually demonstrated either through an improvement in discrimination or detection performance (e.g., Fine & Jacobs,
2002; Seitz & Dinse,
2007) or by negative aftereffects on appearance (color aftereffects, for example). These types of adaptation are thought to promote greater efficiency in the use of low-level visual signals and heightened sensitivity to deviations from the norm (Barlow,
1990; Webster, Werner, & Field,
2005), respectively. More recently however, a very different third type of adaptation has been demonstrated, whereby prolonged intermittent presentation of a stimulus establishes a bias to resolve ambiguous visual input in accord with previous experience, at stimulus onset (e.g., Brascamp et al.,
2008; Haijiang, Saunders, Stone, & Backus,
2006; Klink et al.,
2008; Leopold, Wilke, Maier, & Logothetis,
2002; Long & Moran,
2007; Noest, van Ee, Nijs, & van Wezel,
2007; Pastukhov & Braun,
2008). Rather than exhibiting a short-lived negative aftereffect, which typically follows sustained viewing of a visual feature, the visual system becomes resistant to change, with regard to interpretation of the stimulus, i.e., a kind of
positive aftereffect. Concurrently, it was established that the stabilized percept could be trained to be dependent on a previously unrelated stimulus parameter or “signal,” in an associative learning paradigm (Haijiang et al.,
2006). That is, a bias was learned to interpret visual input in the same way as on previous occurrences of that signal. This signal, therefore, was said to have been “recruited” by the visual system as a cue to visual appearance.