Reasoning in Experimentation

• the hallmark of science is testability of theory
• non-testable theories are not science

• need to pit theories against each other
• theory testing as a series of pruning alternatives

• Madsen and McGaugh: The effect of ECS on one-trial avoidance learning

• meta-Theoretical Question
  • the process of memory consolidation
  • a desire to study the timing and effects of memory consolidation
  • work has continued with biochemical markers for memory consolidation as well as an examination of neural structures involved in consolidation
• prior work
  • ECS disrupts memory consolidation
• alternative explanations
  • ECS induces fear which inhibits action, rather than disrupts memory
• theoretical statement
  • if ECS interferes with memory, then ECS should inhibit step-down avoidance
  • if ECS induces fear, then ECS should facilitate step-down avoidance
• method
  • subjects
    • maze bright and maze dull rats
  • apparatus
    • step down avoidance plate
  • procedure
    • one trial step down
    • shock/no-shock
    • retest 24 hours late
  • Results
    • Shock/no shock Control ECS
    • Avoid/not avoid
      • Avoid 26 8
      • Not avoid 23 39
    • X2 test of association = 11.67
      • (hypothesis of no association is rejected)

• Metatheoretical question
  • motivational effects in learning
  • learned helplessness as a model for depression
• Specific theoretical question
  • phenomena:
    • prior exposure to shock reduces subsequent learning to avoid
  • is the effect of prior exposure to shock due to
    • adaptation
    • learning of incompatible motor responses
• methods
  • Study 1:
    • prior exposure versus not
      • I: no exposure
      • II: 64 trials of 5 seconds
      • III: 640 trials of .5 seconds (same amount of time)
      • IV: 64 trials of .5 secons (same number of shocks)
  • 24 hour delay
    • latency and failures to esape in a shuttle box
      • number of failures % who never escape
      • I: 16 12.5
      • II: 68 62.5
      • III: 55 50
      • IV: 42 37.5
  • Study II: Was the effect due to adaptation or motor learning?
    • I: Curare -- No shock 13 0%
    • II: Curare-shock 47 37.5%
    • III: Hi level of shock 54 25%
  • Study III: passage of time
    • 24 hours 57 50%
    • 48 hours 18 12.5%
    • 72 hours 23 12.5%
    • 144 hours 19 12.5%
    • 1/2 no curare, 1/2 curare (no effects of curare)