objective job conditions, social support and perceived stress among blue collar workers
TRANSCRIPT
JOURNAL OF OCCUPATIONAL BEHAVIOUR, Vol. 3, 79-94 (1382)
Objective job conditions, social support and perceived stress among blue collar workers'
JAMES A. WELLS Washington University
SUMMARY
The hypothesis that perceived supportive relations mediate the association between extra-individual (objective) job conditions and perceptions of occupational stress is tested in a population of blue collar workers. Responses to a mailed questionnaire ( N = 1830) include measures of social support from four sources (supervisor, coworkers, spouse, friends/relatives) and measures of perceived stress (five job pressures and four need deprivations). In addition, company records and expert ratings by company, union and study personnel provide measures of objective job conditions which are commensurate with the subjective reports.
Associations between objective job conditions and perceived stress are significant but modest in size. Controls for age, education, exposure to noxious agents and physical effort on the job do not alter associations between objective conditions and perceived stress.
For five of the nine indicators of perceived stress, social support and objective conditions interact in determining perceptions. This is interpreted as a buffering effect in which social support provides a context that significantly alters perceptions of job conditions. The effect of supervisor support is especially important in regard to buffering.
It is suggested that research on the quality of work should be especially aware of the conditional nature of the relationship between objective job conditions and perceptions.
INTRODUCTION
Over the last two decades, social scientists have placed increasing research emphasis on stressful working conditions: the pressures and deprivations that workers experience on the job. Work stresses are linked to affective measures of the quality of the working experience, e.g. job satisfaction, self-esteem and commitment; to indicators of general well-being, e.g. life satisfaction and happiness; to mental health indicators ranging from affect measures to psychiatric symptoms; and to physical health outcomes such as coronary heart disease and peptic ulcers (Caplan, 1972; Caplan and French, 1968; Caplanetal., 1975; French, Rogers and Cobb, 1975; House, 1972, 1974a, b; House et al., 1979; Kahn and French, 1970; Kahn et al., 1964; Kasl, 1974, 1978; Quinn et af., 1971; Quinn and Shepard, 1974). As a result, researchers are viewing stressful working conditions as negative indicators in and of themselves, as targets for reforms and innovations in the workplace and as the foundation of prescriptive statements of desirable working experiences (cf. O'Toole, 1974; Cooper and Payne, 1978).
'Work on this paper was partially supported by Grant No. 91-37-76-53 from the Employment and Training Administration, U.S. Department of Labor. I am indebted to James. S. House, Ron Burke and Stanislav Kasl for their valuable comments on earlier versions of this paper.
0 1982 by'John Wiley & Sons, Ltd. 0142-2774/82/010079-16$01.60
80 J . A. Wells
Work stress, as generally conceptualized in this literature, involves disturbances in the relationship between the individual and his environment and the consequences this may have for his physical and psychological functioning. French et al. (1975) suggest the problem be seen as a question of fit between the person and his environment where, normally, this fit can be characterized as an equilibrium in which environmental demands do not exceed the person’s abilities nor do the person’s needs exceed environmental supplies. Sometimes, however, the environment poses problems for the individual for which his standard repertoire of responses is inadequate and for which the consequences of not adapting are serious (Sells, 1970). Most studies have focused on role overloads or pressures in which conflicting or excessive demands of the work environment tax the worker’s abilities and adaptive resources (e.g. role conflict, responsibility). More recent research, especially studies based on the person-environment fit model, has equally emphasized role under-loads or need deprivations at work (e.g. lack of prestige or intrinsic challenge).
Although the facile definition stated above belies the extent of disagreement among writers in the stress field, there is near consensus in the recognition that stress is essentially an idiographic and subjective phenomenon (Kasl, 1978). Whether or not a particular work situation is stressful depends ultimately upon how it is experienced and appraised by the particular worker. This formulation has resulted in operationalizations of stressful working conditions that rely nearly exclusively on perceptual measures of stress. This practice is defended by Cassel (1976, p. 11 l ) , among others, who emphasizes the identification of ihe properties of perceived stress that lead to negative outcomes even though the particular circumstances leading to those perceptions differ for different people. Yet, however conceptually appropriate this formulation of perceived stress may be, it has resulted in the neglect of independent or objective assessment of working conditions and such neglect has been criticized on both theoretical and methodological grounds. In a recent review, Kasl (1978) points out that the neglect of objective assessment of working conditions has tended to trivialize much of the research on work stress, since perceived stress is very often operationalized in such a way as to call into question the independence of the measurement of work stress and the particular outcome. This is especially true of affect based outcomes such as satisfaction, anxiety or depression but poses the more general problem of negative response bias in other cases as well. While better operationalizations are clearly indicated and in some cases independent assessment of outcomes (for example medical outcomes) resolves the issue, Kasl suggests that objective measures of working conditions be employed not only to assess their relationship with outcomes but also to assess the anchoring of perceived stress measures in objective data.
Similar arguments have been made on conceptual grounds. House (after the suggestion of McGrath, 1970) suggests a paradigmatic approach, including the anchoring of perceived stress in objective data and the relation of perceptual and objective measures of working conditions to both immediate responses and more enduring outcomes. Thus, in the paradigmatic approach, objective assessments are an integral part of any thorough examination of stressful working conditions. In addition, House emphasizes another set of variables of particular relevance to this discussion. These are individual traits o r social conditions which might modify the relationships among any of the other variables in the stress paradigm. Since the
Stress Among Blue Collar Workers 81
subjective formulation of stress strongly suggests that there will be a weak relationship between objective and perceptual measures of working conditions, and what limited evidence exists substantiates this prediction, a full understanding of stressful working conditions requires the specification of the conditions under which stressful experience is promulgated.
Social support is one such conditioning variable which is finding increasing currency among those studying stressful working conditions. Although definitions of the concept vary somewhat on details, most authors tend to agree on the proposition that primary social attachments provide affective and/or instrumental resources for adapting to stressful situations (Cobb, 1976; Cassel, 1976; Kaplan, Cassel and Gore, 1977). In this vein, the prescriptive literature on organizations suggests that situations which maximize mutual support among workers will minimize stress and dissatisfaction. Seashore’s finding that work group cohesiveness reduces work-related anxiety and the finding by Kahn et al. (1964) that worker’s trust and respect for their role senders decreased perceived role conflict and ambiguity are equally suggestive, but such research is sparse. Furthermore, these studies report only direct relationships between indicators of support and perceived stress (Wellset al., 1977; LaRocco House and French, 1980; Payne, 1980); they do not establish that support mitigates the relationship between objective conditions and perceived stress.
The present study
The present study addresses some of these issues by testing the effect of social support from four sources on the relationships between five measures of objective job conditions and seven measures of perceived stress in a population of factory workers. Although this work is necessarily exploratory, a few simple expectations can be stated. This analysis first explores the relationship between objective assessments and workers’ perceptions of working conditions. Since both objective and perceptual measures are designed to assess similar working conditions, one would expect that the more substantial associations will be between the commensurate measures. Yet, it is not unlikely that perceptual measures will be related to other objective indicators and this paper seeks to delineate the range of objective conditions in which each of the seven perceived stresses are anchored. None-the-less, theory and prior research predict that these associations will not be large in absolute terms.
Secondly, the present analysis will test the relative effectiveness of four sources of social support-supervisor, coworkers, spouse and friends and relatives. This particular focus also affords the opportunity to contrast two theoretical formulations of how social support may operate to buffer stressful perceptions since the two hypothesized mechanisms predict different patterns of relative effectiveness among the four sources.
Informal mediation of organizational expectations refers to the fact that organizations are composed of both a formal and an informal structure. The kinds of pressures and rewards assessed by the measures of objective conditions used here are formally communicated to the worker by those with whom he regularly interacts on the job, typically his immediate supervisor and mutually dependent coworkers. These individuals are in a position to divert the seriousness and
82 J . A . Wells
threatening nature of organizational demands. The better the worker’s informal relations with these individuals (as indexed, for example, by social support), the more likely this is to be true. By this formulation one might expect supervisor support and coworker support to be more important in the mediation of stressful perceptions of job conditions. In contrast, sources of support outside the workplace should be relatively unimportant.
Alternately, one might regard perceived social support as a potentially important component of an individual’s appraisal context. Experiences of the organizational environment of work are filtered through and reconciled with cognitions pertinent to work as well as to other life domains. Insofar as social support indexes some interpersonal milieu that at least partially determines cognitive appraisal, one should expect it to buffer perceptions of potentially stressful conditions. In contrast to the informal mediation of organizational expectation, this formulation leads one to expect that non-work sources of support may be equally important in buffering stress. Thus, the pattern of results in this analysis may suggest the appropriateness of one or the other of these conceptualizations of social support conditioning.
Finally, the present analysis examines the relative effectiveness of social support in mitigating the relationship between a variety of objective and perceptual measures of working conditions. Of particular interest are differences between the two broad types of working conditions: (1) job pressures which largely involve excessive performance demands on the person (e.g. high levels of workload, responsibility, etc.) and (2) job deprivations which largely involve a lack of rewards provided by work (e.g. lack of prestige, control, intrinsic gratification, etc.). There are no grounds for clear expectation in this area. Although by current conceptualizations, both types of stress (overload of demands and underload of gratifications), ought to be mediated by social support.
METHODS
Source of the data
The study population was the entire hourly (non-managerial) workforce of a large tyre, rubber, plastics and chemicals manufacturing plant in a small northeastern U.S. city, including a wide range of blue collar occupations from skilled craftsmen and technicians to relatively unskilled labourers. As part of a larger study of the effects of working conditions on health in the rubber industry a self-administered questionnaire concerning perceived job stresses, social support, health, and exposure to physical chemical hazards was mailed to all 2856 hourly workers in late April, 1974. Repeated follow-ups over eight months resulted in a 70 per cent response rate ( N = 1809) among white males, the group used in the present analysis (see House et al. , 1979, for details of data collection procedures). The small numbers and relatively poor response rates of blacks and women in the plant precluded using their data in this analysis. Extensive analysis comparing questionnaire respondents and non-respondents, and also early versus later responders, suggest that respondents were somewhat older than non-respondents; otherwise the two groups differ little once age is controlled (detailed report available from the author). Age is controlled in all analyses in this study.
Stress Among Blue Collar Workers 83
Some information on job conditions was obtained from company records and job descriptions. For those dimensions not rated by the company, a questionnaire was designed and distributed to expert raters drawn from among company and union officials and members of the research staff who had become familiar with the plant. Ratings were summarized for 21 job classifications comprising the range of jobs in the plant and job classification codes ascertained on the questionnaire allowed the identification of working conditions for all but four of the white male respondents.
Measures of perceived stress
The perceived occupational stress measures are all multi-item questionnaire indices, which derive from previous research (e.g. House, 1972; Caplan et al., 1975) but have been adapted in content and wording to the present study population. Five types of job pressure are assessed, each by a three-item index: (1) responsibility-having too much responsibility for people, process, or products and insufficient human or material assistance; (2) quality concern-concern about not being able to do as good work as one could or should; (3) role conflict-receiving ambiguous and/or conflicting expectations from others at work; (4) job versus non-job conflict-feeling the job interferes with non-work (e.g. family) life; and ( 5 ) workload-reporting a high quantity of work and frequent time pressure.
The study includes 4 measures of self-reported job deprivations or dissatisfactions (or lack thereof as high scores on our measures indicate satisfaction or lack of deprivation). These measures derive from ones previously used by House (1972) and Quinn and Shephard (1974) and assess the different types of perceived rewards or gratifications in the job: (1) intrinsic rewards (8 items assessing the degree to which work is interesting, challenging, varied, etc.); (2) extrinsic rewards (4 items assessing the degree to which the worker’s job pays well, is secure, and has good frint benefits and working conditions); (3) importance rewards ( 5 items assessing the degree to which the worker’s job is important, prestigious, and influential); and (4) control rewards (3 items assessing the degree to which the work pace is not excessively rapid and is subject to worker control).
Measures of social support
The social support measures asked the worker to indicate the degree of perceived support from each of four sources: his supervisor, spouse, coworkers and friends and relatives. The items, adapted from Caplan et al. (1975), were designed to tap both the instrumental and socioemotional components of social support. Two items intended to assess socioemotional support asked how much the worker perceives that another (1) can be relied on when things are tough at work and (2) is willing to listen to his work-related problems. Instrumental support was operationalized as the worker’s perception of the helpfulness of his supervisor or coworkers in getting his job done. However, inter-item analysis indicated that all three measures were measuring a common construct. Presumably, either these items insufficiently distinguish between perceptions of instrumentality and socioemotionality or the attitudes of these workers toward their supporters do not distinguish between these dimensions. In any case, social support is empirically found to be an homogeneous construct, a result not limited to this population, since Pinneau (1975) found the
84 J . A . Wells
same to be true for a stratified sample of occupational groups. Thus, items were added to form an index of social support for each of the four sources.
The spouse support index presented a peculiar problem in that it was appropriate for only the married subset of respondents. Since this condition excluded a considerable number of respondents for any analysis involving spouse support, respondents who were widowed, divorced or never married were assigned the lowest category of social support. Subsequent analysis proved this group to behave in a monotonic fashion with the other categories in conditioning relationships between stress and health (Wells et al., 1977). The sources of support outside the workplace-wife support and friend and relative support-are highly related (0.61 8). Supervisor support and coworker support, sources of support within the workplace, are considerably less correlated both with each other (0.303) and with non-work sources of support (from 0.106 to 0.322). Thus, workers’ perceptions of social support from different sources generally covary only modestly with each other, suggesting that they may have quite different effects.
Measures of objective conditions
The goal of assessing objective job characteristics is to have objective measures of the job which are commensurate with the questionnaire measures assess- ing the workers’ perceptions of job pressures and deprivations. Fortuitously, company records and job descriptions provided some of this information. For those dimensions not rated by the company, a questionnaire was designed and distributed to expert raters drawn from among company and union officials and members of the research staff who were familiar with the plant.
Preferably, one would have specially trained observers rate the objective conditions associated with each and every job in the plant. Neither the resources nor an established methodology existed for accomplishing this in the present study. The alternative strategy was to use ‘expert’ raters who were already familiar with the variety of jobs in the plant: three company employees involved in setting work standards and wage rates, four union employees including two time study engineers and two safety experts and four investigators from the study including two sociologists and two industrial hygienists. To ease their burden the approximately 300 jobs in the plant were categorized into 21 job groups which are homogeneous with respect to the nature of the work activities involved. Several measures relevant to the study were routinely recorded by the company for their own purposes, but since the company ratings did not cover the breadth of job characteristics of interest in this study, a set of items was designed for this purpose. These were presented to the panel of expert judges, the company, union and university personnel noted above, who rated the 21 job groups accordingly. The most reliable ratings were chosen for each item and these were combined to form measures as commensurate as possible with the self-reported measures of perceived stress. Objective rewards was designed to be commensurate with perceived intrinsic, extrinsic and importance rewards; interpersonal demands with perceived responsibility and role conflict; quantitative workload with perceived workload and inversely with control rewards; and qualitative workload with perceived quality concern. An additional indicator of whether the worker is paid a piecework wage versus an hourly wage is employed as an objective condition potentially conducive to perceived workload.
Stress Among Blue Collar Workers 85
Obtaining a commensurate measure of job versus non-job conflict was a problem since it involved judgments of how the job interferes with the workers’ outside commitments. It would be virtually impossible to obtain expert ratings of such conditions. One possibility, though not exhaustive, did exist in ascertaining the shift during which the individual worked. It is well known that shift, especially working the afternoon shift, is a major source of stress due to job interference (Mott et af ., 1965). In the plant under study, employees normally work regular shifts, thus avoiding invalidity of the measure due to changing shifts or working split shifts. The variable used here dichotomizes those workers on the afternoon shift versus those on the other shifts.
RESULTS
Relationships between objective conditions and perceived stress Table 1 shows equations predicting the nine perceived stresses with the most parsimonious set of indicators of objective job conditions. Below these results are multiple correlation coefficients (R’) indicating variance in perceived stress due to the full set of objective predictors and controls for potentially confounding factors; the reduced set of objective predictors and controls; the set of objective predictors only; and the set of control variables only. Potentially confounding factors include age and education which are important selection factors into job classifications, and exposure to agents and physical effort, indicating potentially hazardous and unpleasant working conditions, which might account for relationships between job conditions and reported stress. Although some of these affect perceived stress, a comparison of the variance explained by controls versus that explained by objective conditions in the overall equations shows that controls do not account for the effects of objective conditions. Indeed, the two sets of variables seem to be fairly independent of one another.
Previous analysis has indicated that the ratings of organizational expectations tend to have curvilinear effects on some perceived stresses, for example the effect of objective rewards on perceived responsibility. Curvilinear effects are specified by two terms, one indicating a linear effect and one indicating a quadratic (squared) effect, both of which are required to specify curvilinearity. In the example cited, the net effect on perceived responsibility at any given value of objective rewards (x) is -0 .103~ + 0.036~’. Within the range of objective rewards (-2.56 to 3.57) the net contributions of objective rewards to predicted responsibility range from 0.500 to 0.091 but pass through 0.000 (at x = 0) and 0.067 (at x = 1). Thus responsibility pressures decrease rapidly as objective rewards increase from their lowest value toward zero, but the rate of decrease itself becomes smaller until it completely reverses and becomes positive when the value of objective rewards is about one. Nonetheless the overall pattern is predominantly one of responsibility pressures decreasing over the range of objective rewards. A curve of this type can be seen in Figure 1.
The results among these parsimonious equations cleave faithfully to the pattern expected of commensurate measures, although some non-commensurate effects remain important. Objective reward has effects on job versus non-job conflict, responsibility as well as the three commensurate perceived rewards, intrinsic, extrinsic and importance. These effects however, vary considerably in both size and shape. The relationships between objective rewards and perceived
M
m
-4
Tab
le 1
. E
ffec
ts o
f ob
ject
ive
cond
ition
s on
per
ceiv
ed s
tres
s*
Jobf
non-
job
Rol
e Q
ualit
y R
espo
nsi-
Intri
nsic
E
xtri
nsic
Im
port
ance
C
ontr
ol
?
conf
lict
conf
lict
conc
ern
bilit
y W
orkl
oad
rew
ards
re
war
ds
rew
ards
re
war
ds
z C
onst
ant
a?
-0.0
93
-0.0
12
-0.1
42
-0.0
90
-0.1
79
-0.1
04
-0.2
32
-0.1
02
0.10
9 F
Obj
ectiv
e b
, 0.
0624
Inte
rper
sona
l b
Qua
ntita
tive
b w
orkl
oad
b &
Qua
litat
ive
b,
-0.0
59
wor
kloa
d b,
$ 0.
0655
Shift
b
, 0.
1555
Piec
ewor
k b ,"
rew
ards
b 4
dem
ands
b 4
$
- 0.
1034
-0
.054
-0
.041
0.
0964
0.
0363
0.
0768
0.
0735
0.
0344
0.01
04
0.07
15
0.05
84
0.09
74
0.03
65
0.04
54
- 0.
003
-0.0
495
-0.0
01
0.04
25
-0.0
874
- 0.
1 278
-0
.025
4
0.05
44
0.14
84
0.16
05
0.07
2 0.
070
0.00
3 0.
1134
-0
.138
4 -0
.063
5 -0
.073
4 -0
.105
S
0.18
23
0.15
25
0.72
55
- 0
.288
Tot
al o
bjec
tive
R2
0.09
7 0.
042
0.08
2 0.
100
0.11
7 0.
229
0.10
7 0.
175
0.06
4
Red
uced
set
R'
0.
093
0.03
7 0.
77
0.09
9 0.
114
0.22
7 0.
102
0.17
2 0.
060
Obj
ectiv
e on
lyR
2 0.
027
0.01
2 0.
034
0.05
0 0.
061
0.16
9 0.
047
0.12
8 0.
051
Con
trol
s on
ly R
' 0.
078
0.02
0 0.
053
0.05
7 0.
034
0.06
6 0.
045
0.04
3 0.
008
*Equ
atio
ns in
clud
e on
ly r
educ
ed s
et o
f st
atis
tical
ly si
gnifi
cant
pre
dict
ors.
tC
onst
ant i
nclu
des
effe
cts
of c
ontr
ol v
aria
bles
eva
luat
ed a
t th
eir
resp
ectiv
e m
eans
$C
oeff
icie
nts a
re c
urvi
linea
r (q
uadr
atic
) ef
fect
s.
$Coe
ffic
ient
is s
igni
fica
nt a
t p c
0.05
.
Stress Among Blue Collar Workers 87
intrinsic and extrinsic rewards are strongly curvilinear, but relatively symmetric in form. Both relationships, net of other variables in the equation, increment perceived rewards by about 0.6 at the lower end of the scale and about 0.8 at the upper end, but dip to about -0.01 in the middle range of values on objective rewards. Thus, workers in jobs requiring little skill or experience and having low prestige report rewards almost as high as workers in high prestige high skill jobs, but workers in jobs between these extremes tend to perceive much lower levels of both intrinsic and extrinsic gratification. Importance rewards, in contrast, vary monotonically (though not linearly) with objective rewards rising from a slight negative impact (-0.02) when objective rewards are low to an increment of 0.8 when objective rewards are high. Objective rewards also decrease responsibility pressures, as noted in the earlier example, but curiously inflate job versus non-job conflict. This finding is unexpected but may occur because workers in jobs more likely to be rated highly on objective rewards (e.g. skilled crafts and skilled operatives) were also more likely to be called upon to work overtime and/or rotating shifts and hence more likely to experience job versus non-job conflict.
Interpersonal demands also affect a wide range of perceptions inflating both intrinsic and importance rewards was well as four of the five perceived pressures, but are negatively related to control rewards. With the exception of dependent importance rewards, these effects are linear and interpretation is straightforward, with the strongest impact registering on the commensurate perceptions role conflict and responsibility. The effects on intrinsic and importance rewards are smaller, but interesting in that it appears that objective interpersonal contacts and responsibilities are rewarding as well as pressure-inducing. This is not explained by the tendency for objective rewards and interpersonal demands to be fairly highly correlated, since the former are controlled, although objective demands may indeed be tapping some rewarding aspects of interpersonal contact and responsibility not assessed by the objective rewards measure.
Quantitative workload is inversely related to intrinsic and control rewards with the latter being its strongest effect, ranging from 0.36 under low quantitative workload to - 0.48 when the workload rating is highest. Perceived responsibility shows a slight curvilinear effect of quantitative workload rising from -0.2 under low to a high of zero then falling to -0.35 when workload is high. Surprisingly, quantitative workload has only a slight impact on perceived workload. This result might be occurring due to a peculiar measurement artifact. The expert judges were asked to rate what degree the job requires the worker to work very fast, with little time to finish and the degree of control the worker has over the pace of the work (inversely coded). These ratings tended to indicate that machine paced work made these types of demands, but ratings for jobs paced by the worker were low. However, it appears from the effect of piecework, that self-paced jobs also can induce perceptions of workload pressures due to the type of payment incentive, irrespective of the structured workload inherent in the job itself. Thus, objective workload is not a very potent predictor of its commensurate perception.
Qualitative workload assesses job complexity, mental effort and the degree to which quantity demands may compromise work quality, and tends to have strong positive effects on quality concern and responsibility. It has somewhat smaller effects on perceived rewards, decreasing rewarding perceptions throughout its range but more so at the lower end for intrinsic, extrinsic and importance rewards and more at the upper end for control rewards.
88 J . A. Wells
Shift exhibits only the expected effect that workers on the afternoon (3-1 1 p.m.) shift will experience greater job versus non-job conflict. Piecework, in contrast is positively related to quality concern, responsibility, very strongly to workload, as noted previously, and negatively related to intrinsic rewards, all effects as would be expected due to the pressures of this incentive.
In short, the objective conditions, within the limits of cross-level relationships, give a reasonable accounting of perceptions of work. The pattern of effects in Table 1 is consistent with the commensurate measurements and general expectations as to the direction and relative size of the relationships.
Social support conditioning effects
As argued earlier in this paper, it is quite plausible that social support will condition the effects of organizational conditions and expectations on perceived stress. This statement implies that the observed prediction equations in fact mask an amalgam of effects of objective conditions on perceived stress that are stronger when social support is low but decrease, possibly to zero, as social support increases.
The simple form of such a conditioning effect is illustrated by the equation below:
P = a + b,O + b 2 0 2 + h S + h,OS + b,02S
where P = perceived stress 0 = linear effect of objective conditions
S = social support 0 * = quadratic effect of objective conditions
U S = the interaction (multiplicative) of the linear effect of objective condi-
0 ’S = the interaction of the quadratic effect of objective conditions and social
and where a is the regression constant and b , through b , are metric regression
tions and social support
support
coefficients associated with the variables in the equation.
The conditioning hypothesis is supported by evidence of a significant interaction of the full set of objective predictors in which the effects of one or more objective conditions on perceived stress decrease as social support increases. The equation above illustrates the simple case in which only one objective predictor (exhibiting a curvilinear effect) is tested. The criterion that the full set of interactions be significant implies that the addition of the 0 s and the 0 2 S terms significantly increases the variance explained by the equation. Were more objective indicators involved, then their interactions, plus those already shown, would have to meet this test. In addition, the interaction should indicate a decreased impact of objective conditions on perceived stress when social support is higher. This may be reflected in the reduction of the effect of one or more of the objective predictors in the equation, Again in the simple case illustrated above, this second criterion implies that either b, or b , , or both, are significant and reduce the size (i.e. are opposite in sign) of coefficients b and bZ , respectively. This may be reflected in the reduction of the effect of the type illustrated in the equation above. The upper curve in Figure 1 represents the effects of objective conditions on perceived stress when social
Stress Among Blue Collar Workers 89
High Low
Level of objective job condition
Figure 1. The conditioning effect of social support on the (curvilinear) relationship between objective job conditions and perceived stress
support is zero (i.e. low). This curve is defined by the equation
P = a f b,O f b,02
where b is negative (a negative linear term implies that the function will begin at a point above the bend in the curve and decrease from that point, while a positive coefficient implies that the tail of the graph begins at a point below the bend and increases; positive quadratic terms imply curves that open upward and negative terms imply curves that open downward). A conditioning effect of the hypothesized form might result in an effect such as that shown by the curve in Figure 1 associated with medium support. This curve is defined by the equation
P = a + (-bl + b, S)O + (b, + ( -b5 S ) ) 0 2 + ( - b 3 S )
Note that the interaction effects are opposite in sign to the main effects b, and b,. The weaker effect of objective conditions in this case is evidenced by a flatter, more open curve.
Table 2 displays those equations which exhibit a statistically significant interaction between objective job conditions and social support in predicting perceived stress. These represent results of the analysis of conditioning effects of each of the four supports on each of the nine dependent perceived stresses predicted by objective conditions. In each instance, the overall test of a social support conditioning effect is the test of the improvement in fit of the equation (increment to R 2 ) due to the interaction of support with all objective conditions which significantly affect a perceived stress in Table 2. Two related issues need to be addressed with regard to this criterion. First, this is the most conservative of all possible tests, since wherever redundant or insignificant terms are included, the statistical power of the test is decreased. Secondly, since reduced power implies that
5 a 3
Tab
le 2
. Si
gnifi
cant
sup
port
con
ditio
ning
eff
ects
: m
ain
effe
cts
(M)
and
inte
ract
ions
(I)
&
G-
Su
perv
isor
sup
port
C
owor
ker
supp
ort
Res
pons
ibili
ty
Intr
insi
c re
war
ds
Ext
rins
ic r
ewar
ds
Impo
rtan
ce re
war
ds
Res
pons
ibili
ty
M
I M
I
M
I M
I
M
I
Con
stan
t a*
0.
071
-0.9
95
-0.8
61
-0.7
18
-0.3
06
Obj
ectiv
e b
Jbll
+
-0.1
94
0.00
7 0.
077
-0.0
07J
0.04
5 -0
.006
8 0.
140
-0.0
030
-0.3
749
0.05
79
rew
ards
bJ
b,,$
0.
048
-0.0
01
0.06
69
-0.0
01
O.OS
O§
0.00
1 0.
033
-0.0
01
0.13
09
-0.0
199
Inte
rper
sona
l b
ib 13
0.
1609
-0
.006
0.
024
0.00
2
Qua
ntita
tive
bJb
,,
-0.1
375
0.01
29
-0.0
24
-0.0
03
dem
ands
b d
b 1
4
wor
kloa
d bd
b,,j
t 0.
006
0.00
2
0.04
0 -0
.003
0.
2339
-0
.027
9 -0
.005
0.
001
-0.0
63
0.01
43
-0.0
33
0.00
2 Q
ualit
ativ
e b,
/b,,
0.
250
-0.0
08
0.09
5 -0
.002
9 0.
063
-0.0
01§
0.13
5 -0
.007
9 0.
4749
-0
.069
9 w
orkl
oad
bdb1
8T
-0.1
199
0.00
4 -0
.119
9 -0
.004
-0
.071
0.
002
Piec
ewor
k bd
b,,
0.37
5 0.
009
-0.1
60
-0.0
149
0.23
9 -0
.019
Soci
al s
uppo
rt
b , ,)
-0.0
20
0.09
19
0.06
66
0.06
44
0.04
9
R2
0.
123
0.37
6 0.
214
0.26
5 0.
114
Tab
le 2
(co
ntin
ued)
Spou
se s
uppo
rt
Frie
ndlr
elat
ive
supp
ort
Wor
kloa
d In
trin
sic
rew
ards
W
orkl
oad
Res
pons
ibili
ty
Impo
rtan
ce re
war
ds
M
I M
I
M
I M
I
M
I
Con
stan
t - 1
.561
-0
.27
-0.2
11
-0.1
95
-0.3
18
Obj
ectiv
e re
war
ds
-0.0
88
-0.0
329
0.05
19
0.00
69
-0.1
00
0.00
29
0.09
5 0.
004
0.04
4 -0
.004
0.
0479
-0
.006
Inte
rper
sona
l 0.
1029
-0
.014
9 0.
027
0.00
4 0.
0718
-0
.013
9 0.
1245
-0
.010
-0
.049
-0
.006
de
man
ds
0.02
19
-0.0
049
Qua
ntita
tive
0.03
0 0.
0039
-0
.081
9 -0
.001
-0
.001
0.
0169
-0
.058
0.
0229
w
orkl
oad
0.00
2 0.
0104
Q
ualit
ativ
e 0.
047
0.05
2 0.
173
-0.0
14
0.04
1 0.
007
wor
kloa
d -0
.099
9 -0
.009
-0
.146
9 0.
2689
Piec
ewor
k 0.
8159
-0
.019
-0
.340
4 0.
014
0.79
54
-0.0
25
0.16
3 -0
.003
So
cial
sup
port
0.
0219
-0
.017
0.
012
0.04
0 0.
0749
0.12
2 0.
233
0.12
1 0.
107
0.18
9
*Con
stan
t inc
lude
s ef
fect
s of
con
foun
ding
var
iabl
es e
valu
ated
at
thei
r re
spec
tive
mea
ns.
?In
each
cas
e pa
irs
of b
’s re
fer
to m
ain
effe
ct a
nd in
tera
ctio
n re
spec
tivel
y.
$Coe
ffic
ient
s ar
e qu
adra
tic m
ain
effe
cts
and
inte
ract
ions
. $C
oeff
icie
nt is
sig
nific
ant
at p
<0.
05 (
see
text
).
k?
2 m
m b
3 0
3
09 i
x
rp a
92 J. A. Wells
even sizeable coefficients may fail to appear significant, a problem arises in evaluating the importance of individual effects. This will be accomplished by comparing the size of the effect in the overall equation, its potential significance in the overall equation and its significance if it were the lone interaction term (shown in the table next to each coefficient). Since theory did not predict particular interactions, the appropriate test of conditioning is to include the full set of terms, but the criteria noted above may at least provide suggestive evidence of the differential importance of the conditioning of particular objective predictors.
Given the 36 tests of the hypothesis (four supports x nine perceived stresses), one would expect 1.8 of them to be significant due to chance, but as the table shows, ten significant effects are observed. Thus, under the most conservative test, over one quarter of the tests are statistically significant and confirm the hypothesis. This argument is further strengthened by the fact that the strongest conditioning effects consistently occur among the commensurate predictors of perceived stress. The social support indicators consistently buffer the relationship between objective rewards and perceived rewards, and likewise the relationship between quantitative workload and perceived workload. Only in the case of responsibility does the objective counterpart, interpersonal demands, fail to vary over levels of social support.
There is considerable variation among the four sources of support in terms of theoretical confirmation. Coworker support conditioning effects show only slightly better than chance levels (1 versus 0.9 effects) of occurrence, though the significant conditioning effect confirms the hypothesis. Spouse support exhibits two effects overall, but one of these does not meet the hypothesized criteria, in that the effect of objective rewards on perceived intrinsic rewards is not as hypothesized under high versus low support. Both supervisor support and friend and relative support, however, show substantial numbers of hypothesized effects: four for supervisor support and three for friend and relative support. These results do not lead to a clear confirmation of either of the mechanisms suggested earlier. If support operates via the informal mediation of organizational demands, then one would expect, perhaps, the greater importance of coworker support and certainly not the prevalence of effects of friend and relative support. If support operates via apperceptual mediation, one would wonder why friend and relative support should be so salient where spouse support is not. The patterning of effects of the source does not lend itself to such simple explanation, and without data on either the way in which particular supervisors communicate organizational expectations or the particular content of supportive relationships, as an index of affective milieu, it is impossible to clearly determine the appropriateness of the suggested mechanisms.
In spite of this lack of confirmation of a specific mechanism, the overall pattern of conditioning effects is impressive. Table 2 shows that over one half ( 5 of 9) of the relationships between objective conditions and perceived stress are conditioned by one or more sources of support. Among perceived pressures, conditioning effects are limited to perceived responsibility and perceived workload, while three perceived rewards-intrinsic, extrinsic and importance-are conditioned by one or more sources. Across sources of social support, there seems to be evidence of split between supervisor conditioning of perceived rewards and friend and reiative support conditioning of perceived pressures, but given the small number of tests involved, it is difficult to tell if this is a real trend.
Stress Among Blue Collar Workers 93
DISCUSSION
The theory of behaviour in organizational roles (Katz and Kahn, 1966) predicts that perceptions of objective conditions, in particular organizational expectations, would be conditioned by the quality of interpersonal relationships with role senders. Thus, one is led to expect that social support from supervisors, and /or coworkers should mediate the stress-inducing effects of the objective work environment. Social support theory more generally, especially reflecting the laboratory work of Lazarus (1 966), predicts that social support may operate by establishing an appraisal context within which potentially threatening environments are perceived more benignly. Under this formulation, one would expect any source of support to condition perceptions of objective work conditions.
The findings in this paper do not point clearly to either of these mechanisms, although neither do they substantiate outright rejection in either case. Over one half of all the relationships between objective job conditions and perceived stress tested in this analysis were conditioned by one or more sources of support, the most prevalent conditioners being friend and relative support and supervisor support. Given the predictions of the two suggested support mechanisms, this is an ambiguous pattern of results. The appraisal mechanism might be favoured since spouse sup- port conditioning effects also occur more frequently than chance, but one of the two conditioning effects of spouse support fails to operate in the hypothesized manner, with conditions of high support resulting in stronger rather than attenuat- ed effects of objective conditions on perceived stress. Thus, given the limitations of the present data, the ambiguity of these results cannot be resolved. Future research, in attempting to delineate support mechanisms, should pay particular attention to the nature of communicated expectations and the content of supportive relation- ships, especially with regard to shared values and orientations. Thus, one might be able to distinguish between the two conceptualizations or even find that both are effective mechanisms for buffering stressful perceptions of objective conditions.
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University of Michigan Press, Ann Arbor.
Author’s address: Dr James Wells, Department of Sociology, Box 11 13, Washington University, St. Louis, Missouri 63130, U.S.A.