Typos in Ch. 3

On p. 33, the definition of Aversive stimulus (negative reinforcer) has an error in it, & it's kind of an important one. Here's what it should say:

• A stimulus
• that increases the future frequency of a response that
• its removal (termination) follows.

In the 1st box in the 1st column of p. 36, the gray box at the upper right should say "Go to Chapter 5" & the one at the lower left should say "Go to Chapter 4."

The little diagram at the bottom of p. 52 is incorrect. The phrase in the "after box" should say Sid itches less.

Motivating operations

The concept of motivating operation (MO) is defined and discussed quite differently in Ch. 16 of Applied Behavior Analysis and in Ch. 9 of Principles of Behavior. In the former, Michael defines and describes MOs as having two kinds of effects – behavior-altering (BA) effects and value-altering (VA) effects. BA effects are the temporary effects of the MO on the frequency of current behavior. For example, the MO of food deprivation temporarily increases the frequency of behaviors that have been reinforced by food in the past. VA effects are the temporary effects of the MO on the reinforcing or punishing effectiveness of a stimulus, event, object, or condition. For example, the MO of food deprivation temporarily increases the reinforcing effectiveness of food.

These two effects of an MO are usually presented as if they were two different and independent types of effects that are brought about by an MO. But in my opinion this is an incorrect understanding. An alternative description of an MO's effect, which I prefer, is that MOs have only one kind of effect – a behavior-altering effect. An MO causes a change in the frequency of behaviors that have been reinforced or punished by a stimulus, event, object, or condition in the past. The so-called value-altering effect is not a second, different effect that's independent of the BA effect. We see that when we realize that the value or effectiveness of a reinforcer or punisher can only be understood in terms of whatever changes in behavioral frequency are observed. In other words, when we talk about an MO's value-altering effect, it's really just another way of talking about its behavior-altering effect.

Malott seems to be on the same track, although he doesn't say so explicitly. But he defines MO as "a procedure or condition that affects learning and performance with respect to a particular reinforcer or aversive stimulus." By "affects learning and performance" he can only mean "changes the frequency of the target behavior." So this definition focuses on the MO's BA effects and says nothing about the value or effectiveness of the relevant reinforcer or punisher (which he calls "aversive stimulus"), that is, it says nothing about the MO's VA effect.

As Michael points out in Ch. 16 of ABA, there's still a lot of work to be done before we'll fully understand MOs, especially MO's for punishment. In the meantime, I think Malott's definition is not only simpler to understand, but I also think it's more conceptually accurate because of its focus on the MO's BA effect without claiming that MOs also have a VA effect.

Minor corrections in Ch. 1 of PB

On p. 5, 2nd column, 3rd paragraph below the boxed definition of Behavior, Malott says "And here's a more common definition of behavior:" The more common definition he's referring to is the boxed definition up above. The box should appear after this sentence. What he's saying here is that he finds the dead man test to be a more useful guide as to whether or not something is a behavior rather than the formal definition.

A stimulus by any other name...

On p. 2 Malott explains that throughout Principles of Behavior when the word, stimulus is used, we should understand that it's a shorthand term that might refer to an event, activity, condition, or stimulus as that word is normally used. This is reasonable because, as he says, it can get pretty clumsy to have to say things like "a reinforcer is a stimulus, event, activity or condition that increases the frequency of a response it follows." Much easier to say "a reinforcer is a stimulus that increases the frequency of a response it follows."We just have to remember that in any particular scenario, the stimulus that functions as a reinforcer might be an event, an activity, a condition, or a stimulus in the sense in which that word is normally used.

Be sure you understand that "stimulus" is not a synonym for "reinforcer," nor vice versa.

Another way to think about this is that there are 4 basic kinds of reinforcers. An event could function as a reinforcer. So could a stimulus (in the restricted sense), such as a pleasant taste or aroma. Sometimes a condition or, more specifically, a change in condition, can function as a reinforcer. If it's dark & you can't see, then the behavior of flipping a light switch may change the visibility condition, & that change is a reinforcer. As for activities as reinforcers, I'd expand a little on what Malott says. Rather than an activity functioning as a reinforcer, it's more often the opportunity to engage in a particular activity that functions as a reinforcer. For example, if you wash the dishes, you'll have the opportunity to engage in the activity of playing video games for a while. That opportunity, then, functions as a reinforcer.

I've noticed that there are several places in the book where one of these other terms is used when stimulus should be used instead, in accord with Malott's decision to use stimulus as a shorthand term. An example is in the box at the bottom of p. 54. In my book I've crossed out condition and penciled in stimulus. You might want to do the same thing when you find instances like this.

More on SDs & SΔs

According to Malott, and just about everyone else as far as I can tell, the term, discriminative stimulus, is the "proper" name for the antecedent variable whose abbreviation is S^D. Its opposite, whose abbreviation is S^Δ, doesn't seem to have a proper name. Instead, we're usually told that the abbreviation stands for S-delta, which is really just a way of spelling out S^Δ that makes it clear how it should be pronounced and accommodates keyboards that don't know Greek.

In my opinion, discriminative stimulus should be the label for the category of antecedent variables that includes both S^D and S^Δ. In other words, there are two kinds of discriminative stimuli – S^Ds and S^Δs. An S^D is a stimulus in the presence of which a particular response will be reinforced or punished (depending on whether we're dealing with a reinforcement or punishment contingency), and an S^Δ is a stimulus in the presence of which a particular response will not be reinforced or punished.