At 2:37 PM -0500 7/30/01, Rick Froman wrote:
>I appreciate that behavioristic accounts don't require mechanisms, only
>stimulus-response connections. I teach that negative reinforcement is when
>the removal of a stimulus is followed by an increase in the behavior. But,
>what stimulus is removed in the case of moving the head? If negative
>reinforcement involves the removal of an existing aversive stimulus, how can
>avoidance learning be negative reinforcement if the aversive stimulus never
>occurs? Although I know that the behavioristic approach doesn't require a
>mechanism, it seems that it would require, at least, an observable stimulus.
Negative reinforcement is more generally defined as the strengthening or
maintenance of a behavior by a consequence that involves a reduction in the
frequency of some aversive event.
There are two subcategories:
1) Escape -- the removal of an aversive event as a consequence of
behavior.
This is your use of 'negative reinforcement'.
2) Avoidance -- the prevention or postponement of an aversive event as a
consequence of behavior. In this case (as Sidman demonstrated) the
aversive event need not occur.
A couple of classic articles:
Sidman, M. (1962). Reduction of shock frequency as reinforcement for
avoidance behavior. Journal of the Experimental Analysis of Behavior, 5,
247-257.
An avoidance technique was used in which rats had two levers
available, with independent shock schedules associated with each.
Behavioral patterns in initial conditioning and in the maintenance of the
responses with various response-shock intervals led to the suggestion that
reduction of shock density be considered an important variable in avoidance
behavior.
Herrnstein, R. J., & Hineline, P. N. (1966). Negative reinforcement as
shock-frequency reduction. Journal of the Experimental Analysis of
Behavior, 9, 421-430.
Is a conditioned aversive stimulus necessary in avoidance
conditioning? Or is a reduction in the rate of aversive stimulation alone
sufficient to generate and maintain an avoidance response? Rats were
subjected to an avoidance procedure in which shocks occurred randomly in
time, but a response could reduce the overall rate of shock. Fifteen
acquisition curves, obtained from 16 animals, showed both immediate and
delayed, rapid and gradual increases in response rate; there was no
representative acquisition curve. Response rates were directly related to
the amount by which the response reduced shock frequency. In extinction,
when shock rates were not affected by responding, the response total was
inversely related to the amount by which the response had reduced shock
frequency during prior conditioning, with as many as 20,000 extinction
responses when the shock frequency reduction had been relatively small.
Responding on this procedure shows that avoidance conditioning can occur
without benefit of either classical exteroceptive stimuli or covert stimuli
inferred from the temporal constancies of a procedure. It also shows that
reduction in shock rate is alone sufficient to maintain avoidance.
* PAUL K. BRANDON [EMAIL PROTECTED] *
* Psychology Dept Minnesota State University, Mankato *
* 23 Armstrong Hall, Mankato, MN 56001 ph 507-389-6217 *
* http://www.mankato.msus.edu/dept/psych/welcome.html *
