Michael Caruso made two points about a much-maligned McMaster psychology department webpage which I'll deal with in separate e- mails. Here's his second point, which I'll consider first: > In the second [McMaster] graphic he [the author] > explains that when a negative reinforcer is > present following the response, this is punishment and decreases the > strength of the behavior (no error here). The graphic also says that > the removal of a negative reinforcer following a behavior increases > its strength (no error here either). He calls this escape, where most > intro texts would use the term "negative reinforcement", but escape > strikes me as an acceptable, if less common, term. > > What exactly are the errors in the graphics? >
I believe the error is that the second graphic mixes definition with empirical observation. Historically, negative reinforcement was first defined as punishment (application weakens response ). Then it switched to its current usage (removal strengthens response). If a negative reinforcer is _defined_ as a stimulus whose removal strengthens response, then it turns out to be an empirical observation that such stimuli, when _applied_, often act as punishers. A general question is to ask whether stimuli which are negative reinforcers (when removed) will _always_ be punishers (when applied). Certainly, that's my impression. But through many editions of his textbook the eminent behavior modifier Alan Kazdin has maintained there are exceptions to this rule. For example, in his latest 6th edition of _Behavior Modification in Applied Settings_ (2001), he says in the legend to Figure 2-1 (p. 57): "The figure implies that a particular event that can negatively reinforce behavior can also be used to suppress (punish) some other response that it follows. Although this is usually true, many exceptions exist. It is not necessarily the case that the same event whose removal negatively reinforces a behavior will suppress a behavior when it is presented or vice versa". Long ago, I queried him on his "many exceptions", and got a confusing and (in my opinion) unsatisfactory reply. But whether he's right or not, the conclusion remains: if you _define_ negative reinforcement_ as increasing response strength by removal, then you should not also be defining it as decreasing response strength by presentation. That should be left to empirical observation. But the short answer to what's wrong with the graphics is that students are confused enough by our current definition of negative reinforcement without adding to their misery by stating it in a way which can only confuse further. Current consensus is that a negative reinforcer should never be defined as "a stimulus that reduces the probability of any response it follows" ( which is the what the legend accompanying the first McMaster graphic tells us), not unless we want to totally confuse students and have them flunk the question on the GRE. However, it may be empirically observed to have that effect on many, if not all occasions. Now on to the first point in my next e-mail (q.v.)... 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 http://acsun.frostburg.edu/cgi-bin/lyris.pl?enter=tips _______________________________________________ --- You are currently subscribed to tips as: [EMAIL PROTECTED] To unsubscribe send a blank email to [EMAIL PROTECTED]
