On 11 Nov 2003, Paul Brandon wrote:

> As I said earlier, part of the problem is inherent in the use of the
> topographically similar terms "negative reinforcer" and "negative
> reinforcement", leading to excessive stimulus generalization. The
> solution is to use the term "aversive stimulus" to refer to the event
> (which can function as either a reinforcer or a punisher depending
> upon the contingency) 

This depends on how you define "aversive stimulus". Paul gave this 
definition in his previous post:

"An aversive stimulus is one whose presentation is punishing and 
whose removal is negatively reinforcing" .

I see three problems with the use of the term "aversive stimulus"

1) It's all too often not used in the technical sense given by Paul 
above but instead with inappropriate subjective connotations, as 
something unpleasant. So I think it's best to avoid the term.

2) Paul's definition refers to a special class of events with the 
ability to both punish and negatively reinforce. I referred to 
Kazdin's contention that a stimulus doesn't necessarily have to have 
both properties simultaneously. What do we do with stimuli whose 
presentation is punishing but whose removal isn't negatively 
reinforcing, and vice versa? 

I think it's preferable to define a negative reinforcer as one whose 
removal is strengthening and then ask whether that stimulus can also 
function as a punisher when presented (leave it as an empirical 
question).

3) It's inelegant and convoluted to require that before one can 
designate a stimulus as a negative reinforcer, one has to first show 
that it's an aversive stimulus, which (according to Paul's 
definition) means that it must be shown both that its presentation 
weakens and its removal strengthens. Compare that with the 
straightforward definition that it's a negative reinforcer if its 
removal strengthens.  

Yet even that one leads to widespread misunderstanding among 
students.

-Stephen
___________________________________________________
Stephen L. Black, Ph.D.            tel:  (819) 822-9600 ext 2470
Department of Psychology         fax:  (819) 822-9661
Bishop's  University           e-mail: [EMAIL PROTECTED]
Lennoxville, QC  J1M 1Z7
Canada

Dept web page at http://www.ubishops.ca/ccc/div/soc/psy
TIPS discussion list for psychology teachers at
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