Feist−Feist: Theories of
Personality, Seventh
EditionV. Learning Theories 15. Skinner: Behavioral
Analysis© The McGraw−Hill^477
Companies, 2009jointly and interdependently. To test the reformulated joint influence hypothesis,
Corr predicted that impulsivity should interact with anxiety such that anxious but
impulsive people should respond less to a startle stimulus when viewing negative im-
ages (slides of mutilated bodies) than anxious but nonimpulsive people. By way of
contrast, the original formulation of the RST would predict only that anxious people
would be more responsive to the startle during a negative mood state and that im-
pulsivity would have no effect.
Results supported the joint subsystem hypothesis and contradicted the separa-
ble subsystem hypothesis. That is, participants who were highly anxious but also
impulsive showed a lower startle response especially when viewing negative images,
compared to participants who were highly anxious but not impulsive. In other words,
for highly anxious participants, impulsivity acts as a buffer to being responsive to
negative images. The overall point, nevertheless, still holds: People do not respond
to reinforcers in the same way, and personality is one of the key mechanisms that
moderates their effect.
Reinforcement and the Brain
Recently, researchers have taken reaction sensitivity research a step further by ana-
lyzing individual differences in brain activation as a result of being presented with
rewarding stimuli such as food (Beaver et al., 2006). Brain activation can be studied
in different ways, but researchers in this study used a technology called functional
magnetic resonance imaging (f MRI). f MRI is based on the same technology your
doctor may use if he or she orders an MRI of your body to diagnose a health prob-
lem. Essentially, MRI technology (both f MRI and regular MRI) detects the flow of
oxygen within the brain. Oxygen, carried by the blood, is required for all the
brain’s activities, and the more oxygen there is in one particular area, the more ac-
tivity there is there. John Beaver and colleagues (2006) used f MRI to examine what
parts of the brain were activated when participants looked at various food-related
stimuli and if there were individual differences in personality that predicted this
brain activation. Food stimuli were ideal for this experiment because some foods
are very rewarding (ice cream, cake, etc.), whereas others are not so rewarding
(bland rice, potatoes, etc.).
To conduct their experiment, John Beaver and colleagues (2006) first had par-
ticipants complete the Behavioral Activation Scale (BAS), which is a self-report
measure that captures a person’s general tendency to actively pursue rewards. To get
an idea of what the BAS measures, think about how you would respond to the fol-
lowing item: “I go out of my way to get things I want” (Carver & White, 1994).
Someone who has a high tendency to actively pursue rewards would respond very
positively to this item. After completing the BAS, participants were put into an MRI
scanner that was specially equipped for this experiment. Specifically, the scanner
was fitted with a monitor that allowed the researchers to present pictures to each
participant while a technician was simultaneously scanning the participant’s brain
for activation. Several images were presented to participants while in the scanner
but, for the purposes of this discussion, you can think of them as falling into two
categories: (1) pleasurable (chocolate cake and ice cream sundaes) and (2) bland (un-
cooked rice and potatoes). The researchers were able to determine which area of the
Chapter 15 Skinner: Behavioral Analysis 471