PT - JOURNAL ARTICLE AU - Paul M Bays TI - A signature of neural coding at human perceptual limits AID - 10.1101/051714 DP - 2016 Jan 01 TA - bioRxiv PG - 051714 4099 - http://biorxiv.org/content/early/2016/05/05/051714.short 4100 - http://biorxiv.org/content/early/2016/05/05/051714.full AB - Simple visual features, such as orientation, are thought to be represented in the spiking of visual neurons using population codes. I show that optimal decoding of such activity predicts characteristic deviations from the normal distribution of errors at low gains. Examining human perception of orientation stimuli, I show that these predicted deviations are present at near-threshold levels of contrast. As well as varying in error magnitude, perceptual judgments differ in certainty about what was seen. I demonstrate that variations in the total spiking activity of a neural population can account for the empirical relationship between subjective confidence and precision. These results establish population coding and decoding as the neural basis of perception and perceptual confidence.