Chapter 16 Skinner: Behavioral Analysis 487least one puff in order to ensure equal time for all participants since last exposure to
nicotine. The experimental drug (or placebo) was then administered followed by base-
line mood questions and a light meal in order to prevent nausea. Mood questions
included “Do you feel any good effects?” “Do you feel high?” “Do you feel nervous?”
and so forth. Using a double-blind procedure, participants received either a placebo
or d-amphetamine. The participant then completed a multiple-choice test that pitted
money against smoking to assess baseline levels of the monetary value of smoking.
For example, the participant was given a series of 45 hypothetical choices between
smoking and a progressive amount of money. The point at which the participant
stopped choosing smoking and chose money was referred to as the “crossover point”
and was considered an index of drug-reinforcement efficacy.
Next, a 3-hour progressive reinforcement (PR) session began. Progressive rein-
forcement involves increasing the number of responses that are required before rein-
forcement. In this case, participants had to do a repetitive motor task n-number of
times (starting with 160 and going all the way to 8,400 times) to earn either two puffs
from a cigarette or $1. Which reinforcer they chose was up to them. The idea behind
the progressive nature of the reinforcement procedure was to see how long it took a
person to stop responding (give up trying to get a cigarette or money). This breakpoint
is considered the strength of the reinforcer. If participants’ breakpoint increased more
in the drug condition than in baseline, they were considered responders (to the drug);
if not, they were considered nonresponders. As in the study by Tidey et al., the last
session allowed participants to freely smoke as little or as much as they wished.
The general result was that there was a small effect of d-amphetamine on
increasing smoking. However, there were significant individual differences, and
when one examined the effects for responders compared to nonresponders, the
effect was clear. Smoking breakpoints for the 10 responders became increasingly
higher with increased dosages of d-amphetamine, and money breakpoints became
increasingly lower. In other words, responders were willing to work harder to get
cigarettes under increasing amounts of d-amphetamine. But this pattern of results
did not hold for the eight nonresponders; d-amphetamine had no real effect on their
cigarette smoking. Possible reasons for this effect were seen in the subjective rat-
ings of the effects of the drug: Responders said they felt high and drowsy and that
the drug had good effects. On objective measures (physiological effects), however,
there was no difference between the two groups.
Although this study had no direct evidence, other research provides one plau-
sible explanation for the individual differences seen in d-amphetamine: It results
in individual differences in sensitivities to the neurotransmitter dopamine, which
is associated with most increases in feeling good or having a positive mood. In
other words, responders are more likely to be affected by the stimulant, because
their sensitivity to dopamine is greater. To the extent that personality has a bio-
logical basis (see Chapters 14 and 15), it can affect sensitivity to conditioning. Indeed,
many researchers consider dopamine to be the “positive reinforcement” system.
Mutual Influence Between Personality and Conditioning
In addition to the independent evidence that conditioning affects personality and
that personality affects conditioning, there is also mutual evidence for their influence