Eye Tracking Time Perception

Accurately perceiving how long an event lasts is crucial for many daily activities, from sports to planning. However, our sense of time is easily influenced by various factors, with one key factor being predictability. The general finding in the field of time perception, often termed the temporal oddball effect, is that events that are unusual or less predicted—the “oddballs”—are perceived to last longer than expected. This effect is thought to occur because our brains encode these surprising events less efficiently.

In their recent research paper “Events at Predicted Location Expand in Time“, Shamini Warda and Azizuddin Khan (2026), from the Indian Institute of Technology, used eye tracking technology to investigate how location-based predictions affect the perceived duration of a visual event. The study aimed to bridge a gap in time perception literature, which has traditionally focused on predictions related to a target’s identity rather than its spatial location. The central finding suggests that events appearing at a highly probable, or ‘predicted,’ location are perceived to last longer than events appearing at an ‘unpredicted’ location.

The Important Role of Eye Tracking in Examining Attention

A critical aspect of this research was the use of precise eye-tracking methodology to explore the underlying attentional mechanisms. The authors employed the EyeLink 1000 Plus desktop-mounted eye-tracking equipment, running at a high sampling rate of 1000 Hz, with the experiment designed and hosted using Experiment Builder (both from SR Research). This state-of-the-art hardware and software setup was crucial for controlling and measuring subtle oculomotor responses, providing empirical support for the role of attention in temporal perception.

Key eye-movement measures extracted using SR Research EyeLink Data Viewer were:

• Fixation Duration: Longer fixation durations were observed for events at the predicted location, serving as a reliable marker of sustained overt attentional engagement.
• Saccadic Amplitude: A smaller saccadic amplitude was found for the predicted condition, suggesting less need to shift gaze away from the expected location. Conversely, larger saccadic amplitudes for unpredicted locations reflected a necessary shift in attention.
• Pupil Size: Baseline-corrected mean pupil size was significantly larger during the target offset phase for the predicted condition. Pupil dilation is a well-established index of ongoing attentional processes and predictive cues, indicating increased attentional resources allocated to the predictable event, even after it disappeared.

The meticulous calibration and validation procedures, repeated after every break and aiming for an average error of less than 0.75°, underscore the commitment to precision afforded by the EyeLink system, ensuring the reliability of the oculomotor data.

Paired Comparison Task

In the main experiment, participants judged the duration of a peripheral target image relative to a central standard image in a paired comparison task. Target location was predictable 75% of the time. The results showed a smaller Point of Subjective Equivalence (PSE) for the predicted condition (M=481.54 ms) compared to the unpredicted condition (M=497.65 ms), indicating a relative overestimation of duration for predicted events. This duration expansion was accompanied by the aforementioned eye-tracking signatures: longer fixation duration and smaller saccadic amplitude for the predicted events.

A control experiment was conducted to rule out confounding factors, such as the spatial axis of the predicted locations and the influence of pre-stimulus eye movements. By shortening the interstimulus interval (ISI) to 100 ms, the researchers minimized the possibility of overt orienting before target onset. The EyeLink technology was vital in confirming the control of these eye movements. The core finding of duration expansion at the predicted location was replicated in the control task (Predicted PSE: 486.39 ms vs. Unpredicted PSE: 516.11 ms), even though the difference in fixation duration was no longer significant, suggesting that the effect is driven by implicit attentional bias, which can be either overt or covert.

Attention Mediates Duration Estimation

The study strongly supports the hypothesis that attentional mechanisms mediate the duration expansion of events occurring at predicted locations. The consistent pattern of duration overestimation, coupled with clear and dissociable patterns in fixation duration, saccadic amplitude, and pupil size, leads the authors to suggest that explicit attentional cues are not required to evoke this temporal dilation; attention is implicitly biased towards regularity. The use of the EyeLink system was fundamental, as the eye-tracking data provided the critical objective measures to infer the role of sustained attentional engagement in shaping subjective time perception.

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