Decay of internal reference information in duration discrimination: Intertrial interval modulates the Type B effect

Area of Science:

• Cognitive Psychology
• Neuroscience
• Psychophysics

Background:

• Human perception is influenced by prior stimuli, a phenomenon explained by the internal reference model (IRM).
• The internal reference (IR) within the IRM integrates past and present sensory information, functioning as a form of perceptual memory.
• It remains unclear whether this internal reference representation decays over time.

Purpose of the Study:

• To investigate the temporal decay of the internal reference (IR) within the internal reference model (IRM).
• To test the prediction that IR decay leads to a reduced negative Type B effect in duration discrimination tasks.

Main Methods:

• A two-alternative forced-choice (2AFC) duration discrimination experiment was conducted.
• Intertrial intervals (ITIs) of 1,600 ms (short) and 3,200 ms (long) were used to manipulate the decay of the IR.
• The negative Type B effect, indicative of assimilation towards a preceding standard stimulus, was measured.

Main Results:

• A significantly reduced negative Type B effect was observed with the longer intertrial interval (3,200 ms) compared to the shorter interval (1,600 ms).
• This finding supports the hypothesis that the internal reference decays over time.
• The results indicate that the influence of past stimuli on current perception diminishes as the time interval increases.

Conclusions:

• The internal reference (IR) decays over time, consistent with the decay of perceptual memory representations.
• This temporal decay influences the magnitude of perceptual assimilation effects, such as the negative Type B effect.
• Humans rely on recent past stimuli for current perception, but this reliance decreases as the memory representation decays.