Efficient measurement of dynamic working memory.

Working memory is the ability to maintain a limited amount of information after it has been removed from perception. It is a key cognitive ability, thought to play a role in other cognitive functions, including perception, attention and action. Given its importance, its accurate and efficient measurement is a major goal in working memory research. Here we introduce a novel working memory tracking paradigm, inspired by continuous psychophysics and multiple object tracking. Participants viewed a sequence of stimuli moving along variable paths and were asked to reproduce the path by tracing it on a touchscreen. This reproduction was then compared to the original stimulus to determine error and thus memory performance. Across three experiments, we found that this new method is efficient, reliable and powerful, with only ten trials per condition required for stable performance estimates. We have also shown that the method is only minimally affected by perceptual or attentional confounds. Most importantly, since performance was measured across the trial, this method also allows for the investigation of how working memory changes across time. By averaging equivalent time points across trials, we identified influences from both primacy and recency effects, and quantified performance around particularly important points along the motion path. The working memory tracking paradigm is therefore especially useful when experimental time is limited, experimental conditions are extensive or when the time-course is a key interest. The method also opens up the study of working memory with dynamic stimuli.