Transfer of tilt effects between second-order cues

Second-order cues are visual stimuli that are detectable by human observers, without eliciting a peak in Fourier energy that corresponds to their perceptual properties. The most commonly studied exemplars of second-order cues are those defined by modulation of local contrast (CM). It is widely accepted that such cues are initially detected separately from first-order, luminance modulated (LM), cues. However, after-effects have been shown to transfer between first and second-order cues (LM and CM, respectively). This suggests the existence of a late link in the mechanisms that subserve their processing. To extend the investigation of the mechanisms for processing second-order cues we consider cues defined by modulations in local orientation (OM). Using a tilt-after-effect (TAE) paradigm, we found partial transfer of adaptation between LM and OM cues, confirming the presence of a link between first and second-order cues. Furthermore, we found a partial transfer of TAE between OM and CM cues. These results suggest that, at or before the site of adaptation, information from all visual cues is combined. However, as transfer of adaptation is below 100% in all cases, this is only a partial integration of information.