Two dimensions of personality discussed by Broadbent (1958) as important
sources of variation in performance were introversion-extraversion and
stability-neuroticism. Extraversion was associated with decrements in
performance over time and neuroticism was associated with greater decrements
following stress. Although it is tempting to propose a single model to
account for these effects, what has become clear is that the effects of
personality upon performance require multiple levels of explanation. The broad
dimensions of personality that are consistently identified from investigator to
investigator and shown to be important in different cultures and different
times affect behavior in many different ways.
Before reviewing specific effects of personality, it is necessary to consider
what are the appropriate dimensions to discuss. Personality researchers can be
grouped into those who who study the effect of a single dimension versus those
who develop taxonomic models of multiple dimensions. The first approach results
in alphabetic organizations of personality traits (ranging from Type A
behavior, through Machievelianism to Sensation Seeking) with numerous studies
of convergent validity but few studies of discriminant validity. Within the
second, multivariate-taxonomic tradition are those most concerned with
description and those interested in causal (usually biological) theories. The
descriptive taxonomists have agreed that a set of five dimensions can be
identified consistently across methods. These "big five" dimensions of self
report and peer description have been labeled Surgency, Agreeableness,
Emotional Stability, Conscientiousness, and Culture, (Digman, 1990, Fiske,
1949, Goldberg, 1982; McCrae and Costa, 1987; Norman, 1963; and Wiggins, 1979).
For the more biologically minded, the theories of Hans Eysenck (1952, 1967,
1981, 1991), Jeffrey Gray (1972, 1981, 1982, 1987), or Jan Strelau (1983, 1985)
are appealing descriptions of three fundamental dimensions (Eysenck's
Extraversion, Neuroticism, and Psychoticism; Gray's Impulsivity, Anxiety, and
Aggression; Strelau's strength of the excitory and inhibitory processes, and
balance between these process) that fit within the five factor model [6]. Whether one prefers the three dimensional
biological models or the five dimensional semantic descriptions, it is clear
that all of these dimensions have substantial genetic loadings and that they
are moderately consistent from childhood throughout the life span.[7]
Perhaps because of a greater concern for causal theory among the biologically
oriented taxonomists, there has been more research relating
introversion-extraversion and stability-neuroticism to performance than there
has been for the other dimensions of the "big five". Both of these dimensions
may be associated with individual differences in motivational state. Although
staying within the two-space defined by Introversion-Extraversion and
Neuroticism-Stability, some of the more recent work has examined impulsivity, a
component of I/E and anxiety, a component of neuroticism.
A common assumption when studying human performance is that subjects are alert
and optimally motivated. It is also assumed that the experimenter's task at
hand is by far the most important thing the subject has to do at that time.
Thus, although individual differences in cognitive ability are assumed to
exist, differences in motivation are ignored. For compliant college students
participating in one of only a few psychology experiments, this assumption
might well be true. It is probably less true for psychiatric patients, oil
platform workers at the end of their shift, or deep sea divers under several
hundred feet of water. Indeed, for almost any subject population of interest
it is difficult to believe that the specific experimental task used has an
equally powerful motivation effect upon all subjects. In fact, it is possible,
even with college students, to show that variations in motivational state are
important sources of between subject variation in performance.
Motivational states can be categorized in several different ways.
Conventionally, it has been useful to distinguish between the affective
direction and the energetic intensity of motivation (Humphreys and
Revelle, 1984). More recent work on affective states, however, has suggested
that direction may subdivided into positive and negative components (Watson and
Tellegen, 1985) and that intensity should be considered in terms of energetic
and tense arousal (Thayer, 1989). How these four constructs interrelate is far
from clear. Table 1 presents sample adjectives associated with each construct.
Table 1: Adjectives associated with the measurement of affect and arousal
Thayer's dimensions of arousal Watson and Tellegen dimensions of affect
Energetic Arousal Tense Arousal Positive Affect Negative Affect
energetic fearful alert nervous
full-of-pep jittery active jittery
active tense excited afraid
wakeful clutched-up enthusiastic scared
lively intense attentive guilty
vigorous (not) quiescent interested hostile
wide-awake (not) quiet inspired distressed
(not) sleepy (not) placid determined ashamed
(not) drowsy (not) still proud upset
(not) tired (not) at-rest strong irritable
(not) calm
An alternative four dimensional model of affect and arousal
High Energetic Low Energy/Tension High Depression High Tension
alert drowsy unhappy nervous
full-of-pep dull gloomy jittery
active placid blue afraid
wakeful quiet sad tense
lively serene depressed scared
aroused sleepy angry guilty
excited calm irritable surprised
Thayer (1967, 1978, 1989) has discussed four uni-polar dimensions that he
groups into two higher order constructs of energetic and tense arousal. He
associates energetic arousal with approach behavior and tense arousal with
avoidance behavior. Energetic arousal is increased by mild exercise and varies
diurnally. Thayer (1989) adopts Gray's hypothesis that approach motivation
reflects a sensitivity to cues for reward and that avoidance behavior reflects
a sensitivity to cues for punishment. (See also Fowles, 1980).
Matthews, Jones & Chamberlain (1989) report three mood dimensions that are
sensitive to external stressors: energetic arousal, tense arousal, and hedonic
tone (positive versus negative). They show that energetic arousal is decreased
by the administration of Chlorpromazine, Diazepam or sleep deprivation. Tense
arousal is increased by pain, or watching TV violence, but is reduced by muscle
relaxation.
Watson and Tellegen (1985) have shown that positive and negative affect are
independent of each other and can be used in combination to describe many
psychopathological conditions. Clark and Watson (1991) recently proposed that
differences in positive affect and somatic arousal account for the important
distinction between two affective conditions represented by high negative
affect, anxiety and depression. They suggest that while depression and
anxiety share high negative affect, anxiety also reflects high somatic arousal,
and depression represents lack of positive affect.
Energetic arousal is a non-directional component of motivation in all of these
models of affect. It is also a construct that has been found to be of great
heuristic importance in theories of motivation and cognition ever since
Broadbent (1958). More importantly, in that individuals seem to differ
systematically in their level of energetic arousal, it is a way to link
theories of individual differences to theories of behavior.
Even though Corcoran's (1965) definition of arousal as the "inverse probability
of falling asleep" is immediately understandable, it is clear that the use of
arousal as a construct is problematic. Indeed, some prefer to avoid discussing
arousal and use a broader term, energetics, that subsumes many different
constructs of motivational intensity and the effects of many environmental
stressors (Hockey, Gaillard & Coles, 1986).
Most simply, arousal is a hypothetical construct used to organize the common
behavioral effects of exercise, stimulant drugs, sleep deprivation
(negatively), time of day, time on task and impulsivity (Anderson, 1990). Each
of these separate variables has both a common and specific effect on behavior.
Caffeine and amphetamine both make one more alert and able to respond more
rapidly and for longer periods of time. Caffeine differs from amphetamine in
the locus of its action (post-synaptically versus synaptically) as well as in
some peripheral effects (e.g. caffeine induces hand tremor). It is not
difficult to demonstrate that different manipulations of arousal have somewhat
different effects on the patterning of responses. As an example of a
behavioral dissociation, simple reaction time is facilitated by caffeine but is
also faster for high impulsives (thought to be less aroused than low
impulsives). High impulsives differ from low impulsives in terms of their
speed accuracy tradeoff (Dickman and Meyer, 1988) as well as in terms of
arousal level.
Sanders (1983) discussed the multiple approaches to the study of stress. One
can manipulate the antecedent conditions or examine the physiological
consequences. Similarly, there are at least three ways to study the
relationship of arousal to performance: 1) by varying the situational demands
thought to lead to arousal; 2) by correlating psychophysiological measures to
performance; and 3) by correlating self report measures of arousal with
performance.
The first approach, manipulations of arousal by the use of stressors such as
stimulant drugs, noise, time on task, or time of day, is more commonly used by
experimental psychologists. Broadbent's 1971 review suggested that there were
common effects for some of these manipulations, but also showed that at least
two levels of control processes needed to be invoked to understand all of the
effects. A lower level of control associated with executing well learned
responses was thought to be sensitive to noise or sleep deprivation and an
upper level control process responsible for monitoring the state of the lower
level process was thought to be sensitive to alcohol, extraversion, and time on
task.
Hockey (1986) has proposed that each manipulation produces its own
idiosyncratic state, and that it is a mistake to look for a holy Grail of
unified arousal. Several energetics theorists (Gopher, 1986; Mulder, 1986;
Sanders, 1983, 1986) have made use of Pribram and McGuinness' (1975)
distinction between (phasic) arousal as affecting input processes, (tonic)
activation as affecting motor outputs, and effort as an integrative resource
allocation mechanism (Figure 2).
2) Levels of control associated with reaction time. Different stages of
information processing are affected by different control processes. Modified
from Mulder's (1986) revision of Sanders' (1983) model of reaction time.
After reviewing the parallels and differences between physiological measures
and psychological manipulations, Broadbent (1971) concluded that "We have
therefore no satisfactory physiological reference for the general state which
we are discussing, and which we have revealed purely from behavioral studies.
In some ways it might have been better therefore to avoid using the term
'arousal' for this behaviorally defined concept, but this would probably do too
much violence to the common usage in the literature. The reader should
remember however that we are working solely on a psychological level, and that
the existence of a physiological concept of arousal is merely an interesting
parallel, with no direct contact at present." (p 413). Later he added that "in
complicating the theory of arousal we shall need to know more about the
functions involved in various tasks; behavioral studies and the physiological
attack upon the brain must go hand in hand." (p 447).
The second approach, that of psychophysiological correlates, has proven to be
the most difficult. Partly this is due to confusing a within subject concept
with between subjects measurement (Venables, 1984). It is also partly due to
variations in the time course of different physiological measures. Just
as broad motivational constructs affect behavior at different time courses, so
do narrow constructs of motivational intensity, (e.g., arousal) have different
temporal parameters. EEG measures of arousal have latencies measured in
milliseconds while autonomic measures such as Skin Conductance have latencies
measured in seconds, and body temperature reflects average levels of metabolic
demands during the previous several hours. The disassociations and specific
patterning of responses associated with reactions of the hand, the heart and
the head (Lacey, 1967) make physiologists particularly cautious whenever they
discuss a construct such as generalized arousal.
The third approach is to use self reports of arousal. Thayer (1989) has argued
that subjective estimates of energetic arousal are the most likely to be
associated with performance. He has also reported that self ratings correlate
more with psychophysiological measures than the measures do themselves. This
is what would expect if each psychophysiological measure had specific as well
as general effects, and if subjective awareness of arousal reflected the
general effects.
Matthews (1989) and his colleagues (Matthews, et al., 1989) have done some of
the most extensive work examining the relationship between self reported mood
and performance. They have found consistent, although complicated,
relationships between self reports of energetic arousal and performance on a
variety of simple and complex detection tasks. In addition, they have found
that state measures of self reported arousal interact with trait measures of
individual differences in introversion-extraversion to affect performance on
these tasks.
The use of the term arousal to encompass phenomena ranging across many orders
of temporal magnitude from the milliseconds of the early stages of the evoked
potential (Mulder, 1986) to the effects of 10 minute brisk walks (Thayer, 1989)
to the tendency to seek out stimulation throughout a lifetime (Zuckerman, 1991)
is thought by many to be a mistake. I disagree. I believe that the concept
that changes in resource availability are associated with changes in arousal
allows one to integrate the effect on cognitive performance of stable
personality traits with those of variety of environmental manipulations. This
model has great heuristic value, for it allows an integration of seemingly
unrelated phenomena. Such broad lumping together of disparate effects does
indeed mask differences, however. Each task and each measure has its own
unique variance as well as common variance. What is important is to try to
distinguish the unique from the shared variance. But this is the fundamental
challenge of any theory.
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