Subjective response speed and stimulus intensity in a simple reaction time task

Area of Science:

• Psychology
• Cognitive Science
• Neuroscience

Background:

• Reaction time (RT) is a fundamental measure in cognitive psychology.
• Previous research has explored factors influencing RT, including stimulus properties.
• The potential for post-sensory effects of stimulus intensity on RT remains an area of investigation.

Purpose of the Study:

• To investigate whether visual stimulus intensity exerts post-sensory effects on simple reaction time (RT).
• To determine if subjects are aware of RT variations due to stimulus intensity differences.
• To explore the role of psychophysical intensity control in observing these effects.

Main Methods:

• Employed both phenomenological (subjective ratings) and objective (RT measurement) methods.
• Replicated Sanford's (1970) finding using auditory stimuli, where strong stimuli were rated faster.
• Utilized visual stimuli of varying sizes and luminance, controlling for retinal illumination.

Main Results:

• Auditory stimuli replicated previous findings: strong stimuli rated as faster RTs.
• Small visual stimuli did not produce rating imbalances.
• Larger visual stimuli with the same luminance but greater retinal illumination showed rating imbalances.

Conclusions:

• Post-sensory effects of visual stimulus intensity on simple RT are observable.
• Controlling for the psychophysical intensity of stimulation is crucial for detecting these effects.
• Subjective awareness of RT variations may depend on specific stimulus parameters and retinal illumination.