Experimental Psychology PSY 433

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Experimental PsychologyPSY 433

• Chapter 9
• Conditioning and Learning (Cont.)

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Dressage Example

• http//www.youtube.com/watch?vzKQgTiqhPbw
• The horse responds to hand and leg cues that vary
  by location to signal different moves.
• Horses begin to be trained at age 2 and it takes
  around 13-15 years to be this good (this horse is
  9 years old and is unusual).
• Riders must be trained too, to give the right
  cues and not confuse a trained horse.
• Behavior is shaped.

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Choosing an Experimental Design

• Between vs within subjects designs offer
  different tradeoffs, but there are more than
  practical considerations at stake.
• Choice of design may affect the actual outcome of
  the research.
• Sometimes using a between-subjects and a
  within-subjects design produces different
  results.
• Carryover effects may exist without the
  experimenters knowledge.

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Order Effects

• Order effects (practice effects) experiencing
  one level affects behavior in another level
• Effects of practice, boredom, fatigue
• Example Does content (biology text vs. novel)
  affect proofreading speed? Order is Biology-Novel
• Order effects are controlled in within-subjects
  designs by randomizing or counterbalancing the
  presentation orders.

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Order Effects in Proofreading
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Differential Carryover Effects

• Carryover effects, differential/asymmetrical
  transfer effects occur when experiencing one
  level affects performance on the next.
• The effect of the first level on the second level
  differs depending on which comes first.
• Effect of B following A ? effect of A following B
• Confound occurs when one level consistently
  precedes the other.

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Differential Carryover Effects in Problem Solving
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Classical Conditioning Example

• Grice and Hunter (1964) - human conditioning
• UCS is air puff UR is blinking
• Vary CS intensity (loud or soft tone)
• Done between-subjects or within-subjects
• 500 ms CS 500 ms ISI US
• Varying CS intensity in BS design has no effect
  on CR
• Varying CS intensity in WS design has large
  effect.

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Contrast Between Stimuli

• In a WS design, subjects can compare two levels
  of a stimulus in the same experiment and may
  respond to the two stimuli differently.
• This effect occurs despite the randomization and
  counterbalancing that were used to control for
  differential order effects
• First, choose a random order (LSSLSLLLS)
• Then counterbalance the random order ½ got it,
  ½ got the reverse (SLLSLSSSL)

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Instrumental Conditioning Example

• Bower (1961) 3 groups of rats trained to run
  down an alley (maze) for food.
• Two IVs kind of reward color of maze.
• Reward
• Constant 8 got 8 pellets per maze run
• Constant 1 -- got 1 pellet per maze run
• Contrast got 1 pellet in one colored maze, 8 in
  the other colored maze (black/white)
• All 3 groups ½ got black ½ got white maze.

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ABBA Counterbalancing

• Define 2 conditions A and B or S and L
• In Bowers case, 1 pellet (S) 8 pellet (L)
• Present in order ABBA (SLLS)
• If order effects are linear, they will then be
  distributed evenly across conditions.
• If nonlinear, do not use ABBA, or give practice
  trials first.
• Bower used both ABBA and BAAB.
• Use Balanced Latin Square with 2 groups.