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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.