Abstract
People can update their mental representations whenever the world changes. Updating is usually driven by new sensory input. Interestingly, we can also update mental representations without sensory cues, and we can do this at an appropriate rate. One laboratory paradigm that may require such rate-controlled mental simulation is the motion extrapolation task, where people estimate the current position of an occluded moving object. We explored the functioning of human rate control systems across multiple extrapolation tasks. One possibility is that a common rate controller guides all dynamic updating, an alternative hypothesis is that separate rate controllers guide updating in different modalities and dimensions. In the standard motion extrapolation task, our participants viewed a target moving along a 20 degree track, and then disappear at an unpredictable point. They had to press a button when it reached the end of the track (Figure 1A). In the novel accumulation extrapolation task, participants viewed an empty space filling with gabors. The accumulation process paused before completion. Participants assumed ongoing accumulation, and then pressed when they judged that the process was complete (Figure 1B). The tasks were interleaved, and temporal parameters were matched. We found evidence that a common rate controller guided performance on both tasks. First, task parameters of stimulus velocity, occluded distance and occlusion duration influenced response time in a similar way on both tasks. Second, performance was correlated, so participants who pressed early on one task tended to do so on the other. We conclude that a common rate controller may guide all forms of mental updating. This rate controller is similar to the velocity store that putatively facilitates smooth pursuit, but with a more global function than previously envisaged.
Meeting abstract presented at VSS 2014