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Andrew Hollingworth; Preserved memory for scene brightness following an undetected change. Journal of Vision 2005;5(8):916. doi: 10.1167/5.8.916.
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© ARVO (1962-2015); The Authors (2016-present)
Hollingworth and Henderson (2004) found that through the incremental addition of small rotations of a scene, participants came to consider a significantly different scene viewpoint as an unchanged continuation of the original view. The present study extended this earlier work to the perception of scene brightness and examined the nature of the memory representation retained after an undetected change. Gradual changes in global illumination are quite common in the visual world, such as the illumination change produced by the sun emerging from behind a cloud. To simulate such changes, we incrementally brightened a scene image in a flicker paradigm, with each scene image separated by a brief pattern mask. We first replicated the finding of insensitivity to incremental change: The median luminance at detection was more than a 7-fold increase over the original luminance. To examine memory updating, the scene was incrementally brightened and then returned in one step to the original image. Seventy-five percent of participants detected the change back to the original image and reported only that the scene had become darker. This result suggests that participants may have failed to retain any memory of the original state of the scene. To examine scene memory, we incrementally brightened or darkened the scene. For participants who had not detected the change, we asked them to adjust the brightness of the scene until it matched the first image viewed. Eighty percent of participants adjusted in the correct direction, and the magnitude of adjustment was larger than for a control group of participants for whom the scene did not change. Thus, although memory is updated to reflect changed visual conditions, participants still retain memory for the original state of the environment, all in the absence of explicit awareness of change.
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