Timing of multiple overlapping intervals: how many clocks do we have?

Area of Science:

• Cognitive psychology
• Neuroscience
• Psychophysics

Background:

• Humans accurately perceive short time intervals (1-60s).
• Multiple overlapping intervals can be timed using different modalities.
• Existing models propose either multiple internal clocks or a single clock with arithmetic strategies.

Purpose of the Study:

• To investigate the underlying timescale of human interval timing.
• To determine if a single clock or multiple clocks model best explains timing multiple intervals.
• To test the hypothesis of a nonlinear timescale in interval timing.

Main Methods:

• Two experiments were conducted involving the estimation of overlapping time intervals.
• Participants estimated both equal and unequal, partly overlapping time intervals.
• Computational models based on a validated interval timing theory were used to analyze data.

Main Results:

• A positive correlation was observed between the second interval estimate and stimulus onset asynchrony for equal intervals.
• Similar effects were found with unequal intervals, indicating interval subtraction.
• Experimental findings were consistent with predictions from computational models assuming a nonlinear timescale.

Conclusions:

• Evidence supports a single internal clock model for interval timing.
• The underlying timescale for interval timing is nonlinear.
• A nonlinear timescale model successfully explains systematic errors in estimating overlapping and subtracted time intervals.