Abstract
While most visual working memory studies use static stimuli with unchanging features, in the real-world objects are often dynamic, introducing vast differences in the surface feature information hitting the retina from the same object over time (e.g. changes in orientation, lighting etc). While previous research has shown that change detection is improved if objects obey the rules of physical motion (e.g., Flombaum & Scholl, 2006), here we investigated whether object motion facilitates greater temporal integration of continuously changing surface information in working memory, resulting in a more accurate estimate of an object’s surface feature information.
To evaluate this hypothesis, in Experiment 1 participants (N=33) viewed either one or two circles that were continuously changing colors (2 degrees per frame clockwise of a preset color wheel) for several seconds. At an unpredictable time, the colors disappeared and participants had to report the final color using a color wheel. On half of the trials, the circles physically moved along predefined circular paths on the screen; on the other half of the trials, the circles remained static. We found that the reported color “lagged behind” the physical state of the dots, and that this was more profound when the dots moved than when they were stationary. Critically, we observed that the accuracy of memory responses was significantly better for items in the moving condition compared to the stationary condition, consistent with our hypothesis that object motion facilitates integration of object information. We replicated and extended these results in a second experiment, which utilized slower object movement speeds and slower color changes (N=30).
Together, our data suggest that memory representation is improved —but lagged — for moving objects. This is consistent with an account that motion assists in greater temporal integration and may assist in creating enduring object files.