PSY402 Theories of Learning

1. PSY402Theories of Learning Friday January 17, 2003

2. Importance of CS Strength • CS intensity affects CR strength only when the CS intensity varies. • If the CS strength is always the same, then the CS strength doesn’t affect the size of the CR. • Both dogs must bite in order for their size to matter. • In order for CS intensity to matter, it must signal something.

3. Importance of UCS Strength • Strength of the CR increases with strength of the UCS. • The more intense the air puff, the stronger the eyeblink CR.

4. Salience of the CS • Salience refers to how noticeable a stimulus is – how likely an organism is to notice it in the environment. • Preparedness (evolutionary predisposition) makes some CS more salient than others. • The more salient the CS, the stronger the CR and faster learning.

5. Predictiveness of the CS • Predictiveness refers to how reliably the CS is associated with the UCS. • When two or more CS’s are present, only the most reliable elicits a CR. • When the CS occurs with the UCS more often than the UCS occurs alone, conditioning occurs. • A CS alone weakens conditioning. • A UCS alone weakens conditioning.

6. Blocking • In order to become a CS, a stimulus must provide information not already signaled by other cues. • Surprise is important to conditioning. • Presence of a previously conditioned CS (existing predictive cue) prevents conditioning of a new CS. • Parent threats –fear of the parent prevents learning to fear another cue.

7. Other Implications for Parenting • Threats (CS) should reliably be accompanied by punishment (UCS) or they will be ignored. • Timing of threat (CS) and punishment (UCS) should be close together – not wait until Dad gets home. • Fear of parents (CER) may block conditioning of any other CS.

8. Extinction • Extinction – a method for eliminating a conditioned response. • Extinction paradigm: • Present the CS alone (without the UCS). • With repeated exposure to the CS, it stops being a predictor of the UCS and the CR decreases and eventually stops.

9. What Influences Extinction? • The total duration of exposure to the CS alone, not the number of trials, determines how fast the CR is extinguished. • Shipley measured effects of tone-shock pairing on water licking. • Suppression ratio for licking behavior • 100 sec or 25 sec exposures to CS alone.

10. Spontaneous Recovery • Pavlov – extinction is caused by inhibition of the CR. • Spontaneous recovery occurs when inhibition is temporarily removed. • Continued experience of the CS without the UCS results in long-term suppression of the CR.

11. Conditioned Inhibition • CS+ the original CS • CS- a new CS similar to CS+ • Presentation of CS- without the UCS inhibits the CR. • The idea is that CS- becomes associated with the absence of the UCS – it becomes an “all clear” cue. • CS+ is associated with presence of the UCS.

12. Other Kinds of Inhibition • External inhibition – presence of a novel cue during conditioning inhibits the CR. • Latent inhibition (learned irrelevance) – not really inhibition. • Preexposure to the CS (without the UCS) inhibits later conditioning (+ or -) • Inhibition of Delay – the CR is withheld until an appropriate time.

13. Disinhibition • Disinhibition – removal of inhibition. • The CR increases in strength. • Presentation of a novel stimulus during extinction interrupts it. • Example: Kimmel – disinhibition of inhibition of delay occurred with a novel stimulus. • CR with withheld 4.0 secs but 2.3 secs with a novel stimulus