Experimental Psychology PSY 433

1. Experimental PsychologyPSY 433 Chapter 9 Conditioning and Learning (Cont.)

2. Midterm Results Top score = 32/34Top score for curve = 32

3. Dressage Example • http://www.youtube.com/watch?v=zKQgTiqhPbw • 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.

4. 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 experimenter’s knowledge.

5. 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.

6. (no practice) (practice) Group 1 Biology Novel 1 2 (no practice) (practice) Group 2 Novel Biology 1 2 Order Effects in Proofreading

7. 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.

8. (no practice) (practice) Group 1 Neutral instructions Special instructions 1 2 (no practice) (practice) Group 2 Special instructions Neutral instructions 1 2 Differential Carryover Effects in Problem Solving

9. 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.

11. 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)

13. 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.

16. ABBA Counterbalancing • Define 2 conditions: A and B or S and L • In Bower’s 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.