Perceptual bias is inherent to all our senses, particularly in the form of visual illusionsand aftereffects. However, many experiments measuring perceptual biases may besusceptible to non-perceptual factors, such as response bias and decision criteria. Here wequantify how robust Multiple Alternative Perceptual Search (MAPS) is for disentanglingestimates of perceptual biases from these confounding factors. First our results show thatwhile there are considerable response biases in our four-alternative forced choice design,these are unrelated to perceptual biases estimates, and these response biases are notproduced by the response modality (keyboard versus mouse). We also show that perceptualbias estimates are reduced when feedback is given on each trial, likely due to feedbackenabling observers to partially (and actively) correct for perceptual biases. However, thisdoes not impact the reliability with which MAPS detects the presence of perceptual biases.Finally, our results show that MAPS can detect actual perceptual biases and is not adecisional bias towards choosing the target in the middle of the candidate stimulusdistribution. In summary, researchers conducting a MAPS experiment should use a constantreference stimulus, but consider varying the mean of the candidate distribution. Ideally,they should not employ trial-wise feedback if the magnitude of perceptual biases is ofinterest.
Pre-print #3
