296 Pain Management
even in the absence of the food.That is, the dogs were condi-
tioned to anticipate food at the sound of a bell.
The in”uence of classical conditioning can be observed in
pain patients as well. Consider physical therapy, a mainstay
of treatments for chronic pain patients, where treatment may
evoke a conditioned fear response in patients. A patient, for
example, who experienced increased pain following physical
therapy may become conditioned and experience a negative
emotional response to the presence of the physical therapist,
to the treatment room, and to any contextual cues associated
with the nociceptive stimulus. The negative emotional reac-
tion may lead to tensing of muscles and this in turn may
exacerbate pain and, thereby, strengthen the association be-
tween the presence of the physical therapist and pain.
Once a pain problem persists, fear of motor activities
may become increasingly conditioned, resulting in avoid-
ance of activity. Avoidance of pain is a powerful rationale
for reduction of activity, where muscle soreness associated
with exercise functions as a justi“cation for further avoid-
ance. Thus, although it may be useful to reduce movement
in the acute pain stage, limitation of activities can be chron-
ically maintained not only by pain but also byanticipatory
fear that has been acquired through the mechanism of classi-
cal conditioning. Here we can note how cognitive processes
may interact with pure conditioning. It is the anticipation
that motivates a conscious decision to avoid speci“c behav-
iors or stimuli.
In chronic pain, many activities that are neutral or even
pleasurable may come to elicit or exacerbate pain. As a con-
sequence, they are experienced as aversive and actively
avoided. Over time, more and more stimuli (e.g., activities
and exercises) may be expected to elicit or exacerbate pain
and will be avoided. This process is referred to as stimulus
generalization. Thus, the anticipatory fear of pain and re-
striction of activity, and not just the actual nociception, may
contribute to disability. Anticipatory fear also can elicit
physiological reactivity that may aggravate pain. In this
way, conditioning may directly increase nociceptive stimu-
lation and pain.
The conviction that patients hold that they must remain
inactive is dif“cult to modify, as long as activity-avoidance
succeeds in preventing aggravation of pain. By contrast, re-
peatedly engaging in behavior„exposure„that produces
progressively less pain than was predicted (corrective feed-
back) will be followed by reductions in anticipatory fear and
anxiety associated with the activity (Fordyce, Shelton, &
Dundore, 1982; Vlaeyen et al., 1995). Such transformations
add support to the importance of a quota-based physical
exercise programs, with patients progressively increasing
their activity levels despite fear of injury and discomfort
associated with the use of deconditioned muscles (Dolce,
Crocker, Moletteire, & Doleys, 1986).Operant Conditioning—Contingencies of ReinforcementThe effects of environmental factors in shaping the experi-
ence of people suffering with pain was acknowledged
long ago (Collie, 1913). A new era in thinking about pain
began with Fordyce•s (1976) extension ofoperant condi-
tioningto chronic pain. The main focus of operant learning
is modi“cation in frequency of a given behavior. The funda-
mental principle is that if the consequence of a given behav-
ior is rewarding, its occurrence increases; whereas if the
consequence is aversive, the likelihood of its occurrence
decreases.
When a person is exposed to a stimulus that causes tissue
damage, the immediate behavioral response is withdrawal
in an attempt to escape from noxious sensations. Such re-
”exive behaviors are adaptive and appropriate. Behaviors
associated with pain, such as limping and moaning, are
calledpain behaviors.Pain behaviors include overt expres-
sions of pain, distress, and suffering. According to Fordyce
(1976), these behaviors can become subjected to the princi-
ples of operant conditioning. These behaviors may be posi-
tively reinforced directly, for example, by attention from a
family member, acquaintance, or health care provider. The
principles of operant learning suggest that behaviors that are
positively reinforced will be reported more frequently. Pain
behaviors may also be maintained by the escape from nox-
ious stimulation by the use of drugs or rest, or the avoid-
ance of undesirable activities. In additionwell behaviors
(e.g., activity, working) may not be positively reinforced,
and the more rewarded pain behaviors may therefore be
maintained.
The following example illustrates the role of operant con-
ditioning: When back pain ”ares up, the suf ferer may lie
down and hold her back. Her husband may observe her be-
havior and infer that she is experiencing pain. He may
respond by offering to rub her back. This response may posi-
tively reward the woman and her pain behaviors (i.e., lying
down) may be repeated even in the absence of pain. In other
words, her pain behaviors are being maintained by the
learned consequences.
The woman•s pain behaviors are reinforced by allowing
the person to avoid undesirable activities. When observing
his wife lying on the ”oor, her husband may suggest that they
cancel the evening plans with his brother, an activity that she
may have preferred to avoid anyway. In this situation, her