Discrete Events as Units of Perceived Time
 
 
Here are some demonstrations of the various conditions discussed in the following paper:
Liverence, B. M., & Scholl, B. J. (2012). Discrete events as units of perceived time. Journal of Experimental Psychology: Human Perception & Performance, 38(3), 601-607.
These demonstrations are provided as Quicktime movies, which can be downloaded or viewed directly in most web-browsers. (To download a free Quicktime player, go here.) These movies are a bit large and choppy, but they should be sufficient to illustrate the basic conditions. As compressed versions of the original stimuli, these movies may not preserve the precise spatial and temporal characteristics of the originals.  
 
In visual images, we perceive both space (as a continuous visual medium) and objects (that inhabit space). Similarly, in dynamic visual experience, we perceive both continuous time and discrete events. What is the relationship between these units of experience? The most intuitive answer may be similar to the spatial case: time is perceived as an underlying medium, which is later segmented into discrete event representations. Here we explore the opposite possibility -- that our subjective experience of time itself can be influenced by how durations are temporally segmented, beyond more general effects of change and complexity. In several experiments, we show that the way in which a continuous dynamic display is segmented into discrete units (via a path shuffling manipulation) greatly influences duration judgments, independent of psychophysical factors previously implicated in time perception, such as overall stimulus energy, attention and predictability. It seems that we may use the passage of discrete events -- and the boundaries between them -- in our subjective experience as part of the raw material for inferring the strength of the underlying 'current' of time. In all experiments, subjects viewed visual displays depicting the motion of a simple visual object (a white disc) across a black background, after which they held down a key to reproduce the total duration of the stimulus display.

Expt #1: Path shuffling, Forwards trial (152 KB)  
Expt #1: Path shuffling, Memento trial (148 KB)  
In this experiment, we asked whether and how subjective time might vary for two dynamic displays that differ in terms of event segmentation, but are otherwise equivalent in their low-level visual properties. We used what may be the most powerful cue to event segmentation in simple animations: the insertion of stark spatiotemporal gaps into otherwise smooth motion trajectories. We created simple animations of an object moving along a path, inserting gaps at several points along the way to divide the path into four segments, and then manipulating the order of the segments to produce a pair of trials from each path (a manipulation we term path shuffling). Trials in the Forwards condition preserved the original order of the path segments, such that the gaps were perceived as momentary occlusions of a single, enduring object. In contrast, the segment order was reversed for trials in the Memento condition, such that the gaps were seen to segment the animation into multiple discrete objects and events. Observers judged Memento trials to have taken a shorter amount of time compared with their corresponding Forwards trials, suggesting that event segmentation can lead to subjective time compression. (We also replicated this effect while controlling for eye movements.)  
 
Expt #2: Path shuffling control, Short Jumps trial (120 KB)  
Expt #2: Path shuffling control, Long Jumps trial (136 KB)  
In Experiment 1, the disc made larger spatial "jumps" from the pre-gap to post-gap positions in the Memento condition, compared with the Forwards condition. To show that this 'attentional shifting distance' could not explain our results, this experiment used the same path segments and pre/post-gap distances from Experiment 1, but now the segments were spatially rearranged so that spatiotemporal continuity was disrupted in both conditions. This manipulation resulted in two new conditions: Short Jumps trials (matching the shift-distances from the Forwards trials of Experiment 1) and Long Jumps trials (matching the shift-distances from the Memento trials of Experiment 1). To equate predictability, a "preview ring" was introduced for each shift at each new location at which the disc would reappear. Subjective time did not vary in this experiment, suggesting that the results of Experiment 1 were in fact due to event segmentation.