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Learning, Part II |
| . | EXPERIMENTAL PSYCHOLOGY |
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Learning, Part II |
- General principles: 1) Stimulus Repetition - occurs with repeated stimulus presentation; response decreases sharply at first, then progressively decrease by smaller amounts 2) Response Recovery - If stimulus is withheld, the original (non-habituated) response will recover ("forgetting"); amount of recovery related to length of elapsed time from stimulus presentation 3) Relearning Effects - if original habituation dissapears, it will recur more rapidly during 2nd series of stimulus presentations ("savings") 4) Stimulus Intensity - habituation occurs more rapidly with weak stimuli; repeating some intense stimuli may never lead to habituation 5) Overlearning - further habituation can occur even after there is no measurable change in the decreased response 6) Stimulus Generalization - habituation can be transferred from the original stimulus to a novel, similar stimulus; degree of similarity determines degree of generalization
Ivan Pavlov (Nobel Prize in Medicine and Physiology) - was studying the digestive system (enzymes, neural mechanisms) - an experienced dog would salivate even before the food was presented Classical Conditioning: a reflexive response can be elicited by a previously neutral (ineffective) stimulus if that stimulus is paired with an effective stimulus - Pavlov speculated that many learned behaviors of animals could be traced back to innate behaviors Unconditioned Stimulus (US): a stimulus that reliably elicits an unlearned (innate) response Unconditioned Response (UR): the unlearned response to the US Conditioned Stimulus (CS): any stimulus that does not initially invoke the UR Conditioned Response (CR): a learned response which closely resembles the UR, but is elicited by the CS BASIC CONDITIONING PHENOMENA Acquisition: the process of learning; from the initial pairing of the CS and US, to the increasing strength and reliability of the CR Asymptote: stable maximum level of conditioned responding Extinction: repeated presentations of the CS without the US leads to the reduction and eventual dissapearance of the CR Reacquisition: the rate of learning a CR will be quicker, even if the CR has been extinguished Generalization: the transfer of conditioning to stimuli similar to the CS Discrimination: ability to distinguish between similar stimuli TEMPORAL RELATIONSHIPS BETWEEN CS and US - represented by a line graph of stimulus on-set and off-set
Simultaneous - CS and US begin at the same moment; CR is much weaker than in short-delay conditioning Trace - CS and US are separated by some time interval in which neither stimulus is present (CS and US do not overlap) CS-US Interval - amount of elapsed time between the CS and US in a trace conditioning procedure Long-delay - CS precedes the US by several seconds, but the CS continues until the US is presented Backward - the CS precedes the US, and does not overlap it in time Other Conditioning Phenomenon... Blocking Effect: when prior conditioning with one CS appears to prevent another stimulus from becoming an effective CS Kamin (1968) - used conditioned suppression in rats to light and tone GROUP Blocking Control - conditioning of stimulus T is "blocked" by experience with L - in LT+ trials, stimulus T was redundant in predicting the US - conditioning is not automatic when CS and US are frequently paired - subject is an active, selective learner which pays attention to informative stimuli and ignores uninformative ones
Emotional Responses - exam anxiety (you are not likely to be killed by a number 2 pencil) - higher order associations Immune System - produces antibodies to fight infection by bacteria, viruses, etc. Psychoneuroimmunology: the study of how the cognitive processes affect the nervous and immune systems Ader & Cohen (1975) study in rats:
- two groups: one got saccharin-flavored water, the other got plain water Results - rats in saccharin group had weaker immune response, fewer antibodies produced This effect can also work in reverse, immune enhancement - rats exposed to camphor odor followed by injection of interferon (increases natural killer cells to combat tumors and viruses) - camphor odor alone could elicit increased natural killer cell activity BEHAVIOR THERAPY Phobias: an excessive and irrational fear of an object, place, or situation Phobias do not naturally extinguish over time because: - avoidance of the CS - thinking about the feared object/event (CS) produces anxiety (CR), re-strengthening the association Systematic Desensitization versus Flooding Aversive Counterconditioning: development of an unpleasant CR to stimuli associated with the undesirable behavior "Quitters, Inc.", "A Clockwork Orange"
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