Evidence Basis for Psychological Theories Applied to Mechanisms Involved in Asthma 101conditioned in participants without asthma. For example,
mental arithmetic, a task that can elicit increased respiratory
resistance (although note that Lehrer, Hochron, Carr, et al.,
1996, found mental arithmetic to decrease respiratory resis-
tance), was preceded by the display of a speci“c color and a
different color preceded the appearance of a clear slide (i.e.,
no demand for mental arithmetic); increased respiratory re-
sistance was demonstrated in response to the speci“c color
(D. Miller & Kotses, 1995). In their debrie“ng, 90% of par-
ticipants recalled correctly which color preceded the arith-
metic, but only 17% guessed correctly that the purpose of the
experiment was to examine changes in breathing in anticipa-
tion of performing mental arithmetic, suggesting that condi-
tioning occurred without subjects• awareness.
Rietveld, van Beest, and Everaerd (2000) exposed adoles-
cents with asthma to placebo, citric acid at levels that induced
cough, or citric acid at 50% of cough-inducing levels. The
purpose of their experiment was to examine the role of ex-
pectations: some participants were led to believe the exper-
iment was about asthma, others were told the experiment
was about evaluating ”avors. Cough frequency was greater
among participants who were told the experiment was about
asthma than among those who were told the experi-
ment was about evaluating ”avors. Expectancies are impor-
tant variables in cognitive explanatory models, and the
results of this study suggest that expectancies about the re-
search topic may in”uence symptom perception and report-
ing. An additional interpretation of the results is in terms of
classical conditioned effects. It is likely that cough has a con-
ditioned association with the presence of asthma; a focus on
asthma may make cough more likely, and persons with
asthma are more likely to label cough as indicative of asthma
than are persons without asthma. These studies suggest that
the unintended development of classically conditioned pre-
cipitants should be considered among persons with unex-
plained triggers for their asthma.
In contrast to classical conditioning, operant conditioning
has received little attention as a potentiating or mainte-
nance mechanism for asthma. The role of operant condition-
ing is perhaps more prominent in medically unexplained
conditions such as chronic pain (Romano et al., 1992) or
chronic fatigue syndrome (Schmaling, Smith, & Buchwald,
2000). The illness-related behavior of patients with med-
ically unexplained conditions may be shaped more by the re-
actions and consequences in their environment than is the
behavior of patients with physiologically well-characterized
conditions for which effective treatments exist, such as
asthma. Nonetheless, it is likely that consequences in pa-
tients• environments shape patients• self-management behav-
ior (e.g., medication use), thereby exerting indirect effects on
asthma. These processes await examination in future re-
search.Cognitive and Perceptual ProcessesA model of cognitive processes in asthma would posit that
perceptions, attitudes, and beliefs about asthma can affect
symptom report, medical utilization, and so forth. Several
areas of research inform our understanding of cognitive and
perceptual processes in asthma, including research on the
effects of suggestion on pulmonary function, and compar-
isons of perceived with objective measures of pulmonary
function.Effects of Suggestion on Pulmonary FunctionThe usual method for examining the effects of suggestion on
pulmonary function is to create an expectation for broncho-
constriction by telling participants that they will inhale a sub-
stance that causes bronchoconstriction, when the actual
substance is saline. Isenberg, Lehrer, and Hochron (1992a)
provided a comprehensive review of this literature. Their
summary of the 23 studies (19 used adult participants, 4 used
children) in the literature at that time found that 36% of
427 participants demonstrated objective bronchoconstriction
to suggestion. The typical although not uniform criterion for
bronchoconstriction was a 20% decrement in pulmonary
function. An examination of participant characteristics
(asthma severity, intrinsic versus extrinsic disease, age) po-
tentially related to the likelihood of response to suggestion
did not reveal clear patterns, although more equivocal re-
sults for gender differences were noted, with two of three
studies reporting women to be more responsive to suggestion
than men.
A search for studies on response to suggestion not in-
cluded in the Isenberg et al. (1992a) publication revealed one
additional study (Isenberg, Lehrer, & Hochron, 1992b). Of 33
participants, none showed changes in pulmonary function as
a result of suggestion, which was not consistent with earlier
research. The authors suggested that their use of room air,
compared to the use of saline (which has a slight bronchocon-
strictive effect) in the previous studies, could account for the
divergent results. Suggestion resulted in changes in perceived
air”ow, but again, not in actual air”ow. Certainly an interest-
ing area for further research would be the identi“cation of
individual variables that predict who is likely to respond to
suggestion. If, as Isenberg et al. (1992a) suggest, similar pro-
portions of persons respond to suggestion and to emotions
with bronchoconstriction, might the same persons respond
to both, suggesting a common pathway or mechanism? If a