The impact of spatiotemporal sampling on time-to-contact judgments

Abstract

When motion in the frontoparallel plane is temporally sampled, it is often perceivedto be slower than its continuous counterpart. This finding stands in contrast to humans' ability to extrapolate and anticipate constant-velocitymotion. We investigated whether this sampling bias generalizesto motion in the sagittal plane (i.e., objects approaching the observer).We employed a paradigm in which observers judged the arrival time of an oncoming object. We found detrimental effects of time sampling on both perceived time to contact and time to passage. Observers systematically overestimated the time it would take a frontally approaching object to intersect their eye plane. To rule out artifactsinherent in computer simulation, we replicated the experiment, using real objects. The bias persisted and proved to be robust across a large range of temporal and spatial variations. Energy and pooling mechanisms are discussed in an attempt to understand the effect.

Effects of task-irrelevant texture motion on time-to-contact judgments

“…4a, the observers significantly overestimated TTC, except at the longest designated TTC. This result is compatible with previous studies where overestimation was observed at TTCs smaller than approximately 1,500 ms (Hecht, Kaiser, Savelsbergh, & van der Kamp, 2002;Heuer, 1993;Oberfeld & Hecht, 2008), while underestimation was found at longer TTCs (McLeod & Ross, 1983;Schiff & Detwiler, 1979). In the present experiment, the TTC overestimation decreased as the designated TTC increased from 1,000 to 2,000 ms, as confirmed by a significant effect of TTC.…”

Effects of a moving distractor object on time-to-contact judgments.

“…Although most experiments using a PM task have found an underestimation of TTC (e.g., McLeod & Ross, 1983;Schiff & Detwiler, 1979), cases of TTC overestimation have also been reported, particularly for extrapolation intervals smaller than 1,000 ms (e.g., Hecht, Kaiser, Savelsbergh, & Van der Kamp, 2002;Heuer, 1993;Smith et al, 2001). The extrapolation intervals in the present experiment were about 1,000 ms.…”

Using virtual environments to assess time-to-contact judgments from pedestrian viewpoints

“…One type of coincidence-anticipation tasks is prediction-motion tasks, in which the moving object is occluded from view before it reaches the observer or specified point. The subject then indicates a response at the moment of the object's speculated arrival time [Tresilian 1995;Benguigui et al 2003;Hecht et al 2002]. Another subset of coincidence-anticipation tasks is experiments involving interceptive action tasks, such as catching or hitting balls [Caljouw et al 2004;Senot et al 2003;Servos and Goodale 1998;Tresilian 1993].…”