bio practical reaction time

Reaction Time (RT) in Psychophysiological Research

• Distinction in Variables

  • Two types of variables:
  • Subjective Variables:
    • Assessed via self-report (questionnaires, visual analogue scales).
    • Reflect personal experiences, not measurable externally.
    • Sensitive to biases: demand characteristics, motivation to cooperate.
  • Objective Variables:
    • Measured using devices.
    • Offer a clearer picture of underlying processes.

• Need for Comprehensive Evaluation:

  • Combining objective and subjective measures enhances understanding of psychological phenomena.

Reaction Time Measurement

• Basic RT Assessment:

  • Participants respond to stimuli (e.g., button press) as quickly as possible.
  • Stimuli can be visual or auditory, with several presented randomly.
  • Average reaction times (RT) are calculated in milliseconds (ms).

• Components of RT:

  • Measures:
  • Sensing and Processing Input Stimulus: How quickly information is received and understood.
  • Organizing and Performing Motor Response: The speed of executing the action (e.g., pressing a button).

Differences in RT based on Stimuli

• Modality-Specific Differences:

  • Auditory stimuli processed faster than visual stimuli:
  • Average RT for young individuals:
    • Auditory: approx. 160 ext{ ms}
    • Visual: approx. 190 ext{ ms}
  • Typical visual RT in lab: around 250 ext{ ms}
  • RT gradually increases with age, especially above 50 years.
  • Males typically show a performance advantage (10-20 ms quicker than females).

• Impact of Predictability on RT:

  • Fixed intervals (regular delivery of stimuli) reduce average RT significantly by aiding predictions in sensory processing.

Complexity of Motor Responses

• More complex decisions result in longer RTs:

  • Example:
  • Conner’s Continuous Performance Test:
    • Respond to specific stimuli (e.g., letters) except a target (e.g., letter ‘X’).
  • Go/No-Go Paradigm:
  • Requires identification of stimulus before response, leading to delay.

• Stroop Test Representation:

  • Incongruence (e.g., color name vs. actual color) adds delay compared to congruent scenarios requiring color naming.
  • Unrelated information must be disregarded during processing.

Affective Effects on RT

• Affective evaluations may increase RT:
  • Carl Gustav Jung’s Experiment (1907):
  • Measured RT for topics with negative emotional attachments.
  • Implicit Association Test (IAT):
  • Increased RT indicates inhibition of automatic responses tied to stereotypes.

Advantages of RT Measurements

• Flexibility and Accessibility:
  • RT measurements are adaptable and require minimal equipment.
  • Many RT tests can be conducted online or through easily accessible software tools (e.g., PEBL).

Practical Example: Simple Online RT Test

• Instruction Steps:

  1. Click button upon stimulus activation.
  2. Measure completion times for multiple trials.
  3. Present average RT based on trials.

• Example Results:

  • Trial RTs: 0.249, 0.27, 0.252, 0.279, 0.304

  • Average: 0.2708 ext{ s} (rounded to four decimals).

  • Links for Online Testing:

• RT Test: https://faculty.washington.edu/chudler/java/redgreen.html

• IAT Test: https://implicit.harvard.edu/implicit/selectatest.html

Summary

• RT provides a comprehensive tool for understanding human cognition and processing. Combining subjective self-reports with objective RT measurements offers deeper insights into psychological phenomena, allowing exploration of sensory processing, decision-making, and emotional influences.