Interfering and updating cognitive representations used in judgments of absolute time-to-contact in a prediction-motion task

Participants made judgments about time-to-contact (TTC) with a predictionmotion (PM) task while performing Cooper and Shepard's(1973) cued and non-cued mental rotation task. Using a dual task paradigm, participants mentally rotated an alphanumeric character either before or during the time the object disappeared in the PM task. I assumed that mental rotation occurred either before or during the time imagery was used in PM tasks. Although there were no effects of interference on the PM task, response times to mentally rotate the character increased as a function of character orientation (peaking at 180 degrees) in the non-cued mental rotation condition but not in the cued condition. This finding indirectly supports the notion of a bottleneck process whereby participants are able to store the characteristics of the rotated character and postpone mental rotation until completion of the PM task; thus increasing response time to identify the rotated character.

Moreover, underestimation errors observed in prior studies of PM tasks were not present at large TTC values (6 s) when either the distance or integrated distance and velocity of the object was updated following the disappearance of the object in a PM task. Results suggest that PM tasks involve imagery processes rather than or in addition to optical TTC information and that observer's may internalize the object's visible motion using a memory representation of the object's motion after it disappears.

In summary, the results suggest that imagery processes are involved in judgments of TTC in PM tasks. Further, imagery processes appear to either decay or become inefficient at large values of actual TTC. Distance and integrated distance and velocity cues are potentially useful in updating observer's internal representations in such situations. Therefore, it is important to determine the relative contributions of optical TTC and cognitive operations that underlie TTC judgments in PM tasks. This research has applications to occupations that demand the ability to make spatial judgments involving moving objects. For example, the recent docking collision of the Russian spaceship Progress with the Spektr module of Mir was potentially a result of human error in accurately judging virtual contact. In this manual docking maneuver, the commander must rely on multiple sources of information, some of which may overburden limited processing resources. Automation of certain aspects of the manual docking procedure could serve to reduce cognitive processing load and potentially reduce the probability of human error.