Abstract
The recent past can be a reliable guide to the present state of the world. If you blink while reading this abstract, it is safe to assume that the text will be the same colour when you open your eyes. Our brains might exploit this regularity in the environment to counteract interruptions in perception. We may see evidence of this in a common misperception termed “serial dependence”. When we view similar items over short timescales, we tend to misperceive the most recent stimulus. The errors we make suggest that current stimulus features are blended with those of prior stimuli. Previous work suggested a role for confidence in determining the extent of this effect. This seems logical; if serial dependence involves integration of previous information to smooth over noise in current sensory input, we should consider our confidence in both sources of information. If we were not confident before, why would we incorporate prior information into our current judgement? Conversely, if we are not confident now are we more likely to rely on previous information? We sought to test this more directly by manipulating observer confidence using feedback. In an orientation reproduction task with simultaneous confidence ratings, false negative feedback was applied to reduce prior confidence. Feedback had little impact on low confidence trials, which consistently produced reduced assimilation to prior stimuli. However, previous high confidence trials with false negative feedback produced decreased levels of serial dependence, comparable to low confidence trials. This manipulation constitutes strong evidence that serial dependence is influenced by confidence in prior stimuli. Current confidence was not found to affect serial dependence. In earlier experiments we showed that visual noise in current stimuli can also determine the extent of serial dependence. Combining previous confidence and current noise may allow serial dependence to act according to Bayesian principles.