Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

View full-text article in PMC

. 2015 Apr 21;9:205. doi: 10.3389/fnhum.2015.00205

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

Copyright © 2015 Blakeslee and McCourt.

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

PMC Copyright notice

The snake illusion stimulus used by Blakeslee and McCourt (2012). The stimulus is modeled on Adelson (2000). The test patches in (A, B) share the same luminance. In addition, the upper test patches in both stimuli have the same lower background luminance and the lower test patches share the same higher background luminance. The stimuli differ in the luminances of the more distant regions (the snake undulations) such that the upper test patch in (B) appears to lie beneath a transparent overlay. The bar graph plots the mean (and 95% confidence intervals) of four observers brightness (gray bars) and lightness (white bars) matches for each test patch within the stimulus displays. The test patches are labeled left to right in the order that they appear in the stimuli. Lightness judgments differed significantly from brightness judgments (green bar) only for the upper test patch in (B) where the test patch was seen beneath a transparency. Under this condition subjects were able to make independent inferred judgments of lightness.