PSYC 356 Lecture Notes - Lecture 18: Startle Response, Operant Conditioning Chamber, Contiguity
PSYC 356 Chapter 10: Aversive Control: Avoidance and Punishment
Background:
Realistically, aversive stimulation occurs as often:
Paying bills on time avoids late fees
Marketing the wall may result in spanking
●Vladimir Bechterev (1913)
○Subjects placed fingers on metal plate
○Without instructions trials began:
Warning stimulus—————— Finger shock
○Subjects quickly learned to lift finger when light turned on (AVOIDANCE)
○US exposure dependent upon the subject’s behavior, an instrumental
process; the response is important
Discriminated Avoidance:
●Trials begin w/ a CS (warning stimulus)
●The subject has 2 options
1. Respond (R) correctly before US (shock)
a. CS is turned off
b. US is omitted
AVOIDANCE
2. Fail to respond to CS before US
a. CS remains on
b. US remains on until R
ESCAPE
●Which response is seen early in training?
Aversive Control:
Early Training: Escape dominates
Late Training: Avoidance dominates
Two-process theory:
PROBLEM: since avoidance doesn’t involve getting something how can it be reinforcing?
Two-Process Theory of Avoidance:
Process 1: Classical Conditioning
CS + US in Escape trials ——————- Fear of CS
Process 2: Instrumental Conditioning (depends on process 1)
Response terminates CS (Fear) in Avoidance trials ———— ↓ CS
Thus, responding is reinforced by a tangible event, FEAR
●Fear serves a protective function
●Neuroscientists have discovered that the amygdala plays a central role in fear
○Stimulating the amygdala ↑ fear responding:
■Freezing
■Enhanced startle response
■Heart rate increases
○Lesioning the amygdala ↓ fear responding
■Approach predators
■Loss of conditioned fear
■Inability to condition fear
Document Summary
Psyc 356 chapter 10: aversive control: avoidance and punishment. Subjects quickly learned to lift finger when light turned on (avoidance) Us exposure dependent upon the subject"s behavior, an instrumental process; the response is important. Trials begin w/ a cs (warning stimulus) The subject has 2 options: respond (r) correctly before us (shock, cs is turned off, us is omitted. Avoidance: fail to respond to cs before us, cs remains on, us remains on until r. Process 2: instrumental conditioning (depends on process 1) Cs + us in escape trials - fear of cs. Response terminates cs (fear) in avoidance trials cs. Thus, responding is reinforced by a tangible event, fear. Neuroscientists have discovered that the amygdala plays a central role in fear. In a typical avoidance procedure classical (escape) and instrumental (avoidance) conditioning are mixed. If they are distinct processes, they should also function separately: No escape or avoidance available (but not enough to produce learned helplessness)
