Archive for 04/12/2009

Working memory

JR Minkel has an interesting piece in the Scientific American site (here). He is commenting on the work of W. Zhang and S. Luck who have found that working memory does not fade away but disappears suddenly.

When you go from bed to bathroom on a dark night, a quick flick of the lights will leave a lingering impression on your mind’s eye. For decades evidence suggested that such visual working memories—which, even in daylight, connect the dots to create a complete scene as the eyes dart around rapidly—fade gradually over the span of several seconds. … (Zhang & Luck) tested subjects’ recall for the hues of colored squares flashed briefly on a screen up to 10 seconds earlier. Subjects marked their answer on a color wheel. If memories decay gradually, the guesses should have become increasingly imprecise as time wore on …. Instead subjects went straight from fairly accurate answers to random choices—no better than chance—indicating the memories were decaying all at once. According to Zhang and Luck’s mathematical analysis, most subjects’ memories went “poof” somewhere between four and 10 seconds after the stimulus. …Researchers say a sudden die-off is to be expected if working memories are stored in circuits that feed back on themselves.

I think that working memory and consciousness are related but that it is not clear what the detail of the relationship is. Clearly our conscious perceptions have more resolution, detail and accuracy then our later memories. Is this because of the detail in the working memory?