the impact of trauma and social support on posttraumatic stress disorder: a study of new zealand...

Journal of Criminal Justice, Vol. 25, No. 4, pp. 303-314, 1997 Copyright 0 1997 Elsevier Science Ltd

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THE IMPACT OF TRAUMA AND SOCIAL SUPPORT ON POSTTRAUMATIC STRESS DISORDER: A STUDY OF

NEW ZEALAND POLICE OFFICERS

CHRISTINE STEPHENS AND NIGEL LONG

Department of Psychology Massey University

Palmerston North, New Zealand

IAN MILLER

Police National Headquarters Wellington, New Zealand

ABSTRACT

Police work often involves traumatic situations and efforts toward the prevention of Posttraumatic Stress Disorder (PTSD) focus on posttrauma variables. Empirical evidence and theories of PTSD suggest the importance of social support as a moderator of the effects of trauma, in particular, emotional support and attitudes to expressing emotions. Five hundred twenty-seven oficers of the New Zealand Police responded to a questionnaire to test the hypothesis that social support moderates the effect of traumatic experiences on PTSD symptoms. The prediction that lower social support would be related to higher PTSD scores was supported for social support from peers, supervisors, and outside work, but not for negatively expressed support. The prediction that these aspects of support would interact with traumatic experiences was supportedfor attitudes to expressing emotion at work. These findings suggest that there are important types of ongoing social support, from peers in particular, that can be fostered or provided for by organizations. 0 I997 Elsevier Science Ltd

INTRODUCTION described in the Diagnostic and Statistical Manual of Mental Disorders (American Psychi-

Prevention of PTSD in the Police attic Association, 1994). A notable feature of the diagnosis of the disorder is that it includes

Posttraumatic Stress Disorder (PTSD) is exposure to a traumatic experience. An inherent characterised by the development of a constella- part of much police work is encountering poten- tion of distressing psychological symptoms as tially traumatic situations. Because such experi-

303

304 C. STEPHENS et al.

ences are often unavoidable, much preventive Israeli army (e.g., Solomon and Mikulincer, effort is focused on the development of the dis- 1990; Solomon, Mikulincer, and Hobfoll, 1986; order following the traumatic event. Solomon, Mikulincer, and Waysman, 1991).

The New Zealand Police Trauma Policy (New Zealand Police, 1992) provides for support from independent health professionals for officers affected by trauma. Some incidents re- quire mandatory debriefing, but the referral of individual members is often at the member’s own request (perhaps with the encouragement of supervisors). As Jamieson’s (1992:22) report on the health and trauma support services con- cludes: “It is a fundamental reality that these are only as effective as the willingness of the staff to utilise such services.” There is evidence to suggest that police are less likely to seek help from clinicians, counsellors, or others external to the organization (e.g., Coman, 1993; Graf, 1986), and that this is a reflection of attitudes within the organization that may counter the ef- fectiveness of psychological debriefing as a first stage preventive action. Furthermore, the peer group and supervisors within the organization are important sources of support (Graf, 1986; Greller, Parsons, and Mitchell, 1992). It is the nature of this support that may influence, not only the use of external services by individual officers, but the development of the disorder itself. There is a growing body of evidence that supports the importance of social support as a moderator of the effects of trauma.

Varying types of social support have been measured, but the approach that has consistently found effects has included measures that would be classified as functional by Cohen and Wills (1985). When the function of support was specified, the strongest effects were related to emotional support (Keane et al., 1985; Green and Berlin, 1987). Cohen and Wills (1985) pro- posed that social support moderates the effects of stress when the social support functions en- hance coping abilities specifically related to needs elicited by the stressful event. Cullen et al. (1985) reported that the effects of social support varied according to the types of stress that police officers experienced. Hence, it would be useful to isolate the coping functions of social support that are specifically related to the needs elicited by the experience of trauma. The coping ability that would be supportive in the case of trauma is apparently the need to talk about the experience and to express emotions connected with it. The following section will briefly review the theoretical, clinical, and empirical support for this conclusion.

Assimilating Trauma by Talking About It

Social Support as a Buffer Between Trauma and PTSD

PTSD can develop after any traumatic event, but people exposed to trauma do not necessarily develop the disorder. Extraordinary stressors (like ordinary stressful events) have complex differential effects upon individuals (Barrett and Mizes, 1988; Breslau and Davis, 1987; Green and Berlin, 1987; Sutker, Uddo-Crane, and Al- lain, 1991). In empirical studies that examine a range of variables as moderators of the effects of trauma, social support has been shown to be consistently important. Most of this work has been done in the area of post-combat PTSD, either with American Vietnam War veterans (e.g., Barrett and Mizes, 1988; Boscarino, 1995; Green and Berlin, 1987; Keane et al., 1985), or in the

Horowitz (1993) presents an information processing conceptualization of PTSD in which emotional processing of the trauma is necessary for the intrusion and other PTSD symptoms to decline, The persistence of symptoms in chronic PTSD sufferers could be due to factors that hinder emotional processing, including avoidance.

A common avoidance is refraining from talking about the trauma and Foa, Steketee, and Rothbaum (1989) suggest that a socially supportive environment enhances recovery from trauma through encouragement of discussion of the event. According to van der Kolk (1988:286), “Verbalising the contextual elements of the trauma is the essence of the treatment of acute post-traumatic reactions.”

Studies of Vietnam veterans in the United States have suggested that veterans need to talk openly about and fully explore their combat experiences in a nonjudgmental atmosphere to re-

Trauma and Social Support in the Police 305

cover from trauma (Frye and Stockton, 1982), and that chronic PTSD sufferers had been un- able to assimilate their combat experiences in this way (Solkoff, Gray, and Keill, 1986). Nor- man (1988) interviewed nurses who had served in Vietnam, and found that apart from the intensity of the stressor, the other variable correlated with PTSD was the strength of the social net- work. Typically, those nurses who did not suf- fer from PTSD were more likely to have been in touch with people who had shared the experience and with whom they could discuss their experiences.

In a civilian context, the victims of a hurricane were surveyed soon after the event (Wein- rich, Hardin, and Johnson, 1990) and the most frequently observed coping strategy used by the victims was talking about their experiences. These examples support the view of Williams (1993) regarding the occupational context, that it is helpful to express feelings connected with the trauma and this expression is best shared with those with similar experiences.

Social Support in an Occupational Context

Emotional social support is, thus, likely to be very important in an occupational context in which workers are at risk of traumatic experiences. It has been suggested that people at work are an important source of support for coping with work-related stress (e.g., Beehr, 1985; House, 1981). Graf (1986) considers that peers could be the most important source of support for the police. A study by Kaufmann and Beehr (1989) suggests that among police officers, support from supervisors and from coworkers is more important than support from people external to the organization. This finding could be espe- cially salient to the prevention of traumatic stress in that support at work could come from fellow officers who have had similar experiences.

Nevertheless, there is mixed evidence for the efficacy of social support from peers, and in fact “reverse buffering” (a stronger relationship between stressors and strains under conditions of high social support than under conditions of low support) has been found in some studies (Fusilier, Ganster, and Mayes, 1987; Kaufmann

and Beehr, 1989; Buunk and Verhoeven, 1991). One explanation for these findings is that group cohesiveness has the potential to be supportive or nonsupportive, depending upon the ways in which people in work groups actually commu- nicate with one another (Kaufmann and Beehr, 1989).

Police Attitudes

Indications of the quality of police communication within work groups come from research that has been carried out on police personality and attitudes. There is a general tendency for officers to show little caring or re- spect for others’ feelings (Evans, Coman, and Stanley, 1992), and the sharing of emotional experiences is an aspect of support that is not al- ways found in police culture.

Coman (1993) has shown that a sample of Australian police officers did not use emotion focused coping, tending to use avoidance focused strategies, although many did feel a need to share their emotional experiences with fellow officers. Pogrebin and Poole (1991) also found that police in Britain perceive their emotions as some sort of occupational weakness or hazard, and do not express these feelings to other officers, thinking that they are alone in experiencing them. Police often perceive emotional expression as a character flaw. Fear of not performing well in the eyes of peers influences officers to block feelings in stressful situations (Mann and Neece, 1990) and to continue to suppress emotional reactions or feelings of distaste because “part of their work is to be tough, to suppress emotions” (Gersons, 1989:252).

Thus, police attitudes may be hindering the therapeutic responses necessary for recovery from adverse reactions to trauma, and in this way social support at work could even be en- couraging the development of PTSD in some individuals. It is only a worker’s willingness to risk self-disclosure that allows therapeutic support (McCammon et al., 1988), and the prevail- ing attitudes of some police groups do not allow this. It is important to note here that, as David- son and Veno (1980) have already pointed out, police traits are developed by the work situation

306 C. STEPHENS et al

and, therefore, vary between cultures and between police forces in the same society. There is evidence from a range of countries that suggests that some generalizations may be made about the nature of police work, but the potential for wide variations also must be taken into account. It seems likely that individuals in police groups that do have a strong “toughness ethic,” in which the expression and even the experience of emotion is denied, are likely to be more at risk for developing PTSD following traumatic experiences.

Objectives of the Present Study

In accordance with the evidence outlined above, the main hypothesis to be tested in the present study is that social support (measured as perceived emotional support, content of communications, and attitudes to expressing emotions) will moderate the effect of traumatic experiences on PTSD symptoms. Specific predictions are:

1. There will be a positive relationship between trauma experienced and PTSD symptoms.

2. There will be a negative relationship between social support and PTSD symptoms.

3. There will be an interaction effect between trauma and social support on PTSD symptoms.

The effect of this interaction will be that if social support is higher, the positive relationship between trauma and PTSD symptoms will be weaker.

METHOD

One thousand police officers who worked in one geographical region of the New Zealand Police were surveyed by questionnaire. Ques- tionnaires were distributed through the internal mail of the organization, following an address by a researcher to the district commanders, and an article in the Police Union newsletter. They were returned anonymously to the researcher by prepaid post. The return rate, following one re- minder letter three weeks after the initial post- ing, was 52 percent. Following comments from

some respondents, explaining their nonretums, this low rate was attributed primarily to police officers’ resistance to additional paperwork, dis- trust of the police organization, and cynicism regarding the adverse effects of traumatic experiences. The final sample comprised 527 officers who were representative of the distribution of rank, length of service, type of occupation (general duties, CIB, and traffic safety), gender, and age among all officers of the New Zealand Po- lice. Comparable figures were not available for the level of educational qualification (no school qualifications to university degree or diploma), which was also measured. These variables were included because of the theoretical importance in relationship to PTSD (Stephens and Miller, 1996), or, in the case of branch, owing to a demonstrated relationship with Civilian Mississippi scores in the present study.

Measures

PTSD. The Civilian Mississippi, a version of the Mississippi-PTSD (Keane, Caddell, and Taylor, 1988) was used to measure PTSD symptom scores. The items are based on the Diagnos- tic and Statistical Manual of Mental Disorders (DSM-IV, American Psychiatric Association, 1994) diagnostic scale and clinical experience (e.g., “My daydreams are very real and fright- ening” or “Unexpected noises make me jump”) and answered on a five-point scale with appro- priate anchors from “never” or “not at all true” (one) to “very frequently” (five). The respondents in the present study were requested to an- swer according to “the way you have been feeling during the PAST MONTH.” The past month is considered to be a time span that includes present symptoms and could also incorpo- rate symptom-free phases during which a person functions well, although underlying problems remain (Williams, 1993). Symptom scores may range from thirty-five to 175 (forty-five to 161 in the present sample). A cut-off score on the scale, above which respondents may be classi- fled as PTSD cases, has been calculated at 103 for nonclinical samples (Eustace, 1994). In the present study, the scores on the Civilian Missis- sippi were used as continuous symptom scores


only. A test of the psychometric properties of the Civilian Mississippi used with 668 civilians (Vreven et al., 1995) reported acceptable reliability coefficients (.86M = 64.31). Coefficient alpha was .90 (M = 78.99, SD = 15.77, N = 508) in the present study.

Traumatic stressors. The traumatic stress schedule (Norris, 1990) was used as a basis for the collection of data on past traumatic events. The nine items in this instrument were: robbery, physical assault, sexual assault, tragic death, motor vehicle crash, combat, tire, natural disaster, and other hazard. Five other items in the same format, but relating specifically to police duties, were added. These items were based on the circumstances listed by the New Zealand Police Trauma Policy for which mandatory debriefing is now required: deliberate killing by police officers, deliberate or accidental death of a police officer, accidental death or injury of a member of the public by a police officer, work with victims of disturbing homicides, atten- dance at severe accidents, and disaster victim identification work. Two additional items were included to record ongoing or chronic stressors and any other source of trauma that the respon- dent had experienced. The questions were asked in terms of personal experience of the event, with examples, such as: “Did anyone ever take anything from you by force or threat of force such as in a robbery, mugging, or hold-up?’ or “Have you been present at an incident in which a police officer was deliberately or accidentally killed?’ Each item included information on re- peated experience, time since the event, and whether the event was before or outside of police work. No method of calculating a trauma score provided higher correlations with Civilian Missis- sippi scores, in the present sample, than simply summing the number of traumatic experiences. This score (possible range from zero to sixteen) was accordingly used as the measure of trauma.

Social support. Four measures of social support were initially used:

1. Emotional support from peers, supervisors, and nonwork sources (three scales of four items

each from Caplan et al., 1975). Each item was measured on a five-point Likert scale, and each set of four items was summed into an index of support from that source. The possible range of scores was from one to five, with higher scores indicating stronger perceptions of support. The coefficient alpha estimates of reliability for these scales ranged from 80 to 88. Content of communication with supervisors and peers (eight scales based on those developed by Beehr, King, and King, 1990). These indices were formed by computing the mean item score for each of four subsets of items: nonjob communications, negative communications, positive communications, and communications about disturbing experiences. The scores on each index ranged from one to five. There are four indices for each source of communication (peers and supervisors). Coefficient alpha reliability estimates ranged from .73 to 89. The ease of talking about trauma at work was measured with two items in which respondents rated, on a three-point scale, how easy it is to talk about traumatic experiences-details or feelings-at their work place. The items were combined into one measure named “Talk,” which was negatively correlated to scores on the Civilian Mississippi (4516) = -.39, p < .OOl) with a coefficient alpha of .81. Possible scores ranged from zero to four, with a higher score indicating greater ease of talk. To measure attitudes about expressing emotion at work, an exploratory scale specifically related to police work was created. This scale comprises four items, and the three possible responses to each item ranged from acceptance of the expression of personal emotions (score = 2), through avoidance techniques such as hu- mor and more acceptable emotions such as generalized anger (score = 1), to physical avoidance and suppression of feelings (score = 0). Scores on each item were summed to pro- vide an expression of emotion index for each individual. Higher scores indicate greater acceptance of the expression of personal emotions at work. The coefficient alpha estimate is low at S2. The simple correlations among variables in the present study showed that the attitude scale was significantly and positively related to other theoretically-related aspects of social support, such as talking about traumatic experiences (4516) = .33, p < .OOl). Attitude was also significantly and negatively correlated to scores on the Civilian Mississippi


(r(516) = -.20, p < ,001). As low reliability attenuates observed correlations (Nunnally and Bernstein, 1994) (this effect is compounded in the use of product terms [Jaccard, Turrisi, and Wan, 1990]), any estimates of correlations and regressions using product terms that include these measures will be conservative. Owing to the initial support for the construct validity of the attitude scale, it was retained for further analysis and investigation, although any results from analyses including this scale are to be interpreted with additional caution regarding the inconsistency of the measure.

For the purposes of the present study, a principal components analysis of the thirteen social support variables was used to create composite variables that would reflect the shared variance accounted for by these scales. Nonwork social support was removed owing to low correlations with the other variables and a low communality in the solution. Extraction of components with an eigenvalue greater than 1, and orthogonal ro-

tation (SPSS varimax), resulted in four components that accounted for 68 percent of the total explained variance. The final solution may be seen in Table 1, which shows the twelve variables entered into the final analysis. Five variables, related to support from the supervisor, loaded onto the first component, which was named accordingly “supervisor support.” Simi- larly, four of the peer support variables plus ease of talking about trauma, loaded onto component two, named “peer support.” Communi- cation with peers about disturbing experiences and negative communication with peers, loaded with negative communication with supervisors onto a third component that was interpreted as “negative support.” Consequently, these social support variables were combined into three composite variables: peer support, supervisor support, and negative support that were used with attitudes to expressing emotion and nonwork social support to test the relationships between trauma, PTSD, and social support.

TABLE 1

COMPONENT LOADINGS AND COMMUNALITIES FOR PRINCIPAL COMPONENTS EXTRACTION AND VARIMAX ROTATION ON TWELVE %XIAL SUPPORT VARIABLES (N = 516)

Variables

Component 1 Component 2 Component 3 (Supervisor (Peer (Negative

SUPPOrt) Support) SUPPOfl) Component 4 Communality

Supervisor personal communcation

Supervisor positive communication

Supervisor social support

Supervisor disturbing communication

Peer personal communication

Peer social support Talk Peer positive

communication Peer negative

communication Supervisor negative

communication Peer disturbing

communication Attitude Eigenvalue Cumulative percent

variance accounted for

.82

.76

.74

.68

.21 .76 .16 -.24 .71

.15 .75 .Ol .15 .60

.15 52 .06 .50 .55

.36 .52 -.lO .30 .49

- .27

.49

.12

.08 4.06

33.80

.22

.19

.22

.lO

.13

-.17

.49

.Oi 1.59

47.10

.08 -.08

.oo .23

-.09

.45

.85 -.09 .80

.72 -.02

.56 .41 -.03 .85 1.40 1.08

58.90 67.90

.79

.73

.73

.Q4

.30

.73

.66

.60

.76


Analysis of Data

The statistical package SPSS/PC (Norusis, 1992) was used to run a hierarchical regression analysis assessing three blocks of variables: the first block to control for the contribution to the variance on the Civilian Mississippi of the demographic variables and trauma; the second to assess the additional contribution of the social support variables while controlling for each other; and the third, a series of interaction terms to test for the effect of higher order interactions between the variables as predicted. Interaction effects were modeled using product terms, and variables that appeared in the product terms were cen- tered around their mean to avoid multicollinearity problems (Jaccard, Turrisi, and Wan, 1990).

Following initial regression runs, eleven multivariate outliers were removed from the sample, leaving 5 16 cases in the following analyses. For these analyses, an alpha level of .05 was set. Two-tailed p values are also reported for probability levels lower than .05.

RESULTS

Descriptive Statistics

Table 2 describes the distributions of all nominal variables in the present study. ANOVAs

TABLE 2

SUMMARY OF NOMINAL VARIABLES (N = 516)

Variables

Gender Male Female

Rank Constables Sergeants Inspectors and above

Branch General duties CIB Traffic safety

Education No school qualifications School certificate University entrance or above Certificate or diploma University degree, etc.

Percentage

89.0 11.0

72.5 24.8

2.7

69.5 21.9

8.6

10.3 28.3 39.4 14.8 7.2

were conducted on these variables with Civilian Mississippi scores as the dependent variable. There were no significant differences between the groups on gender, marital status, ethnic group, or rank. The only significant difference between groups was for levels of educational qualifications, F(2,504) = 3.15, p < .05, and the branch of the organization, F(2,503) = 4.68, p < .Ol.

Table 3 provides the means, standard deviations, and simple correlations with Civilian Mis- sissippi scores of all continuous variables. Only negative support is not significantly correlated to Civilian Mississippi scores. All simple correlations among the variables were below .5, except for age and length of service (r(5 16) = .80).

Trauma experienced while off duty was significantly but weakly related to Civilian Missis- sippi scores (r(498) = .17, p < .OOl). Trauma experienced on duty as a police officer was more strongly correlated to Civilian Mississippi scores (r(498) = .29, p < ,001). Regression of Civilian Mississippi scores on the scores for each traumatic experience, to control for covari- ante, showed that four types of events were related significantly to Civilian Mississippi scores: a police officer’s friend’s death (beta = .14, p < .Ol); having experienced a robbery, mugging, or hold-up (beta = .14, p < .Ol); chronic distress at work (beta = .14, p < .Ol); and other experiences, which included suicides, infant deaths, and body recoveries (beta = .17, p < .OO 1, ad- justedR’ = .12, F(16,489) = 5.31,~ < ,001).

TABLE 3

MEANS, STANOARD DEVIATIONS, AND CORRELATIONS (PEARSONS r), WITH CIVILIAN MISSISSIPPI SCORES, FOR ALL

CONTINUOUS VARIABLES IN THE ANALYSIS (N = 516)

Variables Mean SD r

Age 35.19 8.19 Length of service 11.67 8.51 Peer support 11.15 2.27 Supervisor support 10.44 2.50 Negative support 8.25 1.57 Nonwork support 4.11 .82 Attitude 4.92 1.42 Trauma 4.60 2.27 Civilian Mississippi 78.25 14.23

.13*

.16** -.39” - .24’*

.05 - .24’- -.20**

.31 ??*

*p < .Ol. "p < ,001 (two-tailed)


Regression of Civilian Mississippi Scores on Social Support Variables

Step one. The first block to be entered into the regression equation included trauma, length of service, gender, education, and branch of the service.

Age was omitted because of its high correlation with length of service. Following initial analyses, branch was reduced to a dichotomous variable by collapsing the traffic and CIB cate- gories into one, which was compared to the general duties group. This was done because the numbers were too low and the means were equivalent on these two groups. Level of educational qualifications was collapsed into three groups: no qualifications, high school qualifications, and tertiary qualifications. From these groups two dummy dichotomous variables were created: in one, those without qualifications or school qualifications are contrasted with those with tertiary qualifications (Education2); in the other, having school and tertiary qualifications together is contrasted with no qualifications (Education 1).

Trauma and the demographic variables explained 10 percent of the variance (adjusted R*) on the Civilian Mississippi (F(6,509) = 10.75, p < .OOl). Trauma showed the greatest impact on the Civilian Mississippi (beta = .29); higher trauma scores were associated with higher Ci- vilian Mississippi scores. The other significant contributor in the first step was branch (beta = .09). The positive impact that branch had on Ci- vilian Mississippi scores may be interpreted as higher scores on average for those in the traffic or CIB branches of the police. Education, gender, and service were not significant.

Step two. Five social support variables (attitude, peer support, supervisor support, negative support, family support) were then entered into the equation (Table 4). The social support variables together explained a further 17 percent in unique variance (R2 change) and the total variance explained in Civilian Mississippi scores was 27 percent (adjusted R2, F( 11,504) = 18.34, p < .OOl).

Of the control variables, trauma maintained its significant relationship with Civilian Missis-

sippi scores. Branch became nonsignificant with a drop in beta to .04 suggesting that the relationship is mediated by levels of social support in the branches. The correlation coefficient for Education1 became significant, possibly because correlated social support variables are suppressing irrelevant variance in the relationship between education and Civilian Missis- sippi scores. The negative relationship is such that those without educational qualifications are at risk for higher Civilian Mississippi scores than those with school or tertiary qualifications.

All social support variables showed beta weights significantly different from zero: attitude (-.09), peer support (-.31), supervisor support (-. 1 l), negative support (.157), and family social support (-. 13).

Step three. Product terms (trauma X support variable) were created and entered individually in the third step. The interaction term attitude by trauma had a beta weight that was signifi-

TABLE 4

HIERARCHICAL MULTIPLE REGRESSION OF CIVILIAN MISSISSIPPI SCORES ON TRAUMA, DEMOGRAPHIC AND FIVE

SOCIAL SUPPORT VARIABLES SHOWING STANDARDIZED REGRESSION COEFFICIENTS (BETA), R, R*, ADJUSTED R*,

AND R* CHANGE (N = 516)

Predictors Step 7 Step 2 Step 3

Controls Trauma Branch Service Gender Education1 Education2

Social Support Attitude Peer support Supervisor support Negative support Family social support

Interaction Attitude x trauma

Multiple R Total R* Adjusted R2 R* change

.29*” .22***

.09 .04

.02 .Ol -.oo .oo -.12 -.I3 -.09 -.ll

- .09* -.31 ??** -.ll’

.16*** -.13**

.34*** .53***

.ll .29

.lO .27

.11*** .17***

.22=*=

.05

.Ol

.oo -.12* -.li

.lO - .31 ??=* -.lO

.16*** -.13

- .09’

.54***

.29

.26

.007*

‘p < .05. ??*/J < .Ol. ??**p < Dol.


cantly different from zero. The results for this entry into the third step is shown in Table 4, which displays beta for the interaction term and multiple R, R2, and adjusted R2, and R2 change for its entry to the equation. The interaction term contributed significantly to an increase in multiple R, and explained a further .7 percent of the variance, which was increased to 28 percent (F(12,503) = 17.40, p < .OOl).

The form of this interaction was explored by splitting each variable at the median to form a dichotomy of high and low scores, and the mean Civilian Mississippi score of each high and low group was plotted. Figure 1 shows the form of the interaction: Trauma is positively related to Civilian Mississippi scores, and this relationship is significantly weaker if attitude is high, which is the predicted form of the interaction.

DISCUSSION

The mean and variance on the Civilian Mis- sissippi scores of these police officers repro- duces the findings for a group of civilians in New Zealand who had experienced a natural disaster (Eustace, 1994). This suggests that the prevalence of PTSD symptoms in the New Zealand Police is similar to that of a group of civilians who have undergone at least one potentially traumatic experience. The scores on the trauma schedule show that traumatic experiences at

Figure 1. The Form of the Interaction Between Trauma and Attitudes to Expressing Emotions on Civilian Mississippi Mean Scores.

work are more likely to be related to police officers’ PTSD symptoms, although as would be expected, there is some effect from experiences outside work.

The first prediction that the PTSD symptoms would be positively correlated with the number of traumatic experiences was supported. The correlation between trauma and PTSD symptoms was not expected to be strong, owing to the variance in mental health outcomes attribut- able to other factors. Notwithstanding this ex- pectation, simply summing the number of potentially traumatic events is a crude measure that may not capture many other important aspects (such as the immediate effect of different experiences on different individuals) of the traumatic experience. Measures of trauma that could include these aspects may show a stronger correlation. Nevertheless, previous work has demonstrated that the number of different experiences in itself has an appreciable effect on PTSD symptoms (e.g., Goenjian et al., 1994; Vrana and Lauterbach, 1994) and such findings were supported in this study.

The second prediction that PTSD symptoms would be negatively related to social support was supported, for social support from peers, social support from supervisors, and for social support from outside work. The social support variables together contributed a further 17 percent to the variance in PTSD scores. This is higher than the magnitude of predictive power (around 10 percent) found in many reports of the effects of social support on stress outcomes (Solomon et al., 1987). Peer support, which included the ease of talking about trauma, showed the strongest impact on PTSD symptoms; the strength of the impact was greater than that of trauma.

The second prediction was not supported for negatively expressed support, which was positively related to PTSD symptoms. The simple correlations did not show a relationship between negative support and PTSD, but negative support became significantly and positively related to PTSD symptoms when controlling for other demographic and social support variables. This result suggests that other aspects of social support measured (possibly support from peers) were accounting for the beneficial effects of


talking about negative aspects of work. The det- rimental effects of such communications, therefore, were clarified when these more beneficial aspects were controlled for. The positive relationship indicates that communication about negative aspects of work with either peers and supervisors is associated with higher symptoms, suggesting that only some types of communication are supportive; other types are related to poor health outcomes. Solomon et al. (1987) discuss the evidence for a distinction between social support and social interaction in which negative interactions are seen, not as part of a support continuum, but as stressors. There are many aspects of social interactions that may be burden- some and it is important to identify the specific types of social support that are beneficial.

Attitudes to expressing emotion are another aspect of social support that was expected to have an effect on PTSD symptoms. The weaker main effect of attitudes on PTSD was interpreted as an average effect of the significant interaction with trauma (Aiken and West, 1991). It was predicted that social support would moderate the relationship between traumatic stressors and PTSD. The predicted effect was that, under conditions of high social support, the positive relationship between trauma and PTSD outcomes would be weaker. When controlling for the effects of all other social support variables, it was found that only attitudes to expressing emotion significantly moderated the impact of trauma on PTSD symptoms. The form of this relationship was as predicted.

The increases in explained total variance were low; however, McClelland and Judd (1993) have demonstrated that tests for interaction effects in field studies have very low efficiency. Even when reliable moderator effects are found, the increase in explained variance is often discon- certingly low and any effect found is likely to be attenuated. Thus, this result points to the importance of police officers’ positive attitudes toward expressing emotions at work in ameliorat- ing the effects of trauma.

This study was cross-sectional in design, and firm conclusions cannot be drawn concerning the causal direction of these results. It is very likely, for example, that the positive relationship between negative social support and PTSD

symptoms is the result of those with higher PTSD symptoms feeling more disgruntled about their work because of their symptoms. The present results support theories used to make predictions about relationships and the findings are congruent both within the study and with other current findings in the field. There is a basis for making some suggestions concerning organizational practice, and for investment in further longitudinal study to confirm these results.

The present study was focused on the prevention of PTSD symptoms in the occupational recovery environment. The findings demonstrate that police officers who feel able to express their emotions at work and allow others to do the same are less likely to develop PTSD symptoms following increasing numbers of traumatic experiences. The main effects of social support on PTSD show a positive effect for emotional support and talking about trauma, and a delete- rious effect for communications that focus on negative aspects of the work. These findings, taken together, suggest that there are important types of ongoing social support, from peers in particular, that may be fostered or provided for by organizations.

A type of intervention that has been developed over recent years, particularly in police forces in the United States, has been named “peer support.” The peer support model encour- ages officers to talk about their traumatic experiences with trained peer supporters who are sympathetic and supportive members of the work group. These officers are not expected to be psychologists, but are support persons primarily there as someone to talk to (Violanti, 1996). The peer supporters may also help edu- cate officers about normal stress reactions, which are framed as positive coping resources, rather than pathology. Peer support groups are formally established by the organization that also provides training for carefully selected staff members. Approaches to the provision and management of peer support groups is described in more detail in Reese and Horn (1988) or Pa- ton (1994). The provision of peer supporters has direct beneficial effects for individual officers who use the service, and indirect effects on groups of officers who feel supported by the organization. Officers may also experience a


change in attitude as such support systems en- able them to talk about traumatic experiences in a positive light.

REFERENCES

Aiken, L. S., and West, S. G. (1991). Multiple regression: Testing and interpreting interactions. Newbury Park, CA: Sage Publications.

American Psychiatric Association. (1994). Diagnostic and statistical manual of mental disorders. 4th ed. Washing- ton, DC: American Psychiatric Association.

Barrett, T. W., and Mizes, J. S. (1988). Combat level and social support in the development of posttraumatic stress disorder in Vietnam veterans. Behavior Modi$cation 12: 100-15.

Beehr, T. A. (1985). The role of social support in coping with organizational stress. In Human stress and cognition in organizations: An integrated perspective, eds. T. A. Beehr and R. S. Bhagat. New York: John Wiley & Sons.

Beehr, T. A., King, L. A., and King, D. W. (1990). Social support and occupational stress: Talking to supervisors. Journal of Vocational Behavior 36:6 I-81.

Boscarino, J. A. (1995). Post-traumatic stress and associated disorders among Vietnam veterans: The significance of combat exposure and social support. Journal of Trau- matic Stress 8:3 1 l-36.

Breslau, N., and Davis, G. C. (1987). Posttraumatic stress disorder: The etiological specificity of wartime stressors. American Journal of Psychiatry 144578-83.

Buunk, B. P., and Verhoeven, K. (1991). Companionship and support at work: A microanalysis of the stress reduc- ing features of social interaction. Basic and Applied Psy- chology 12:243-58.

Caplan, R. D., Cobb, S., French, J. R. P., Jr., Van Harrison, R., and Pinneau. S. R., Jr. (1975). Job demands and worker health. Washington, DC: US. Department of Health, Education and Welfare.

Cohen, S., and Wills, T. A. (1985). Stress, social support, and the buffering hypothesis. Psychological Bulletin 98: 310-57.

Coman, G. J. (I 993). Trauma, stress and coping of police @cers: An Australian police survey. Paper presented at the Stress and Trauma in the Workplace Conference, Adelaide, Australia, April.

Cullen, F. T., Lemming, T., Link, B. G., and Wozniak, J. F. (1985). The impacts of social supports on police stress. Criminology 23:503-22.

Davidson, M. J., and Veno, A. (1980). Stress and the police- man. In White collar and professional stress, eds. C. L. Cooper and J. Marshall. London: John Wiley & Sons.

Eustace, K. L. (1994). Cyclone Bola: A study of the psychological after-effects. Unpublished master’s thesis, Mas- sey University, Palmerston North, New Zealand.

Evans, B. J., Coman, G. J., and Stanley, R. 0. (1992). The police personality: Type A behavior and trait anxiety. Journal of Criminal Justice 20:429-4 1.

Foa, E. B., Steketee, G., and Rothbaum, B. 0. (1989). Be- havioral/cognitive conceptualizations of post-traumatic stress disorder. Behavior Therapy 20: 155-16.

Frye. J. S., and Stockton, R. A. (1982). Discriminant analysis of posttraumatic stress disorder among a group of Viet Nam veterans. American Journal of Psychiatry 139:52-56.

Fusilier, M. R., Ganster, D. C., and Mayes, B. T. (1987). Ef- fects of social support, role stress, and locus of control on health. Journal of Management 13:517-28.

Gersons, B. P. R. (1989). Patterns of PTSD among police officers following shooting incidents: A two-dimensional model and treatment implications. Journal of Traumatic Stress 2~241-57.

Goenjian, A. K., Najarian, L. M., Pynoos, R. S., Steinberg, A. M., Petrosian, P., Sterakyan, S., and Fairbanks, L. A. (1994). Posttraumatic stress reactions after single and dou- ble trauma. Acta Psychiatrica Scundinavica 90:2 14-2 I.

Graf, F. A. (1986). The relationship between social support and occupational stress among police officers. Journal of Police Science and Administration 14: 178-86.

Green, B. L., and Berlin, M. A. (1987). Five psychosocial variables related to the existence of post-traumatic stress disorder symptoms. Journal of Clinicrrl Psychology 43: 643-49.

Greller, M. M., Parsons, C. K., and Mitchell, D. R. D. (1992). Additive effects and beyond: Occupational stressors and social buffers in a police organisation. In Stress and well-being at work, eds. J. C. Quick, L. R. Murphy, and J. J. Hurrell, Jr. Washington, DC: American Psycho- logical Association.

Horowitz, M. J. ( 1993). Stress-response syndromes: A review of posttraumatic stress and adjustment disorders. In International handbook of traumatic .stress syndromes, eds. J. P. Wilson and B. Raphael. New York: Plenum Press.

House, J. S. ( 1981). Work stress and social support. Read- ing, MA: Addison-Wesley.

Jaccard, J., Turrisi, R., and Wan, C. K. (1990). Interaction effects in multiple regression. Newbury Park, CA: Sage Publications.

Jamieson, J. A. (I 992). Developing an occupational health and trauma support service for the New Zealand Police. In Trauma and tragedy. Public Safety Personnel Sympo- sium conducted at the World Conference of the Intema- tional Society for Traumatic Stress Studies. Amsterdam, June.

Kaufmann, G. M., and Beehr, T. A. (1989). Occupational stressors, individual strains, and social supports among police officers. Human Relations 42: 185-97.

Keane, T. M., Scott, W. O., Chavoya, G. A., Lamparski, D. M., and Fairbank, J. A. (1985). Social support in Viet- nam veterans with posttraumatic stress disorder: A com- parative analysis. Journal of Consulting and Clinical Psychology 53:95-102.

Keane, T. M., Caddell, J. M., and Taylor. K. L. ( 1988). Mis- sissippi scale for combat-related posttraumatic stress disorder: Three studies in reliability and validity. Journal of Consulting and Clinical Psychology 56:85-90.

Mann, J. P., and Neece, J. (1990). Workers’ compensation for law enforcement related posttraumatic stress disorder. Behavioral Sciences and the Law 8:447-56.

McCammon, S., Durham, T. W., Allison. E. J., and Will- iamson. J. E. (1988). Emergency workers cognitive ap- praisal and coping with traumatic events. Journul of Traumatic Stress 11353-72.

McClelland. G. H., and Judd, C. M. (1993). Statistical diffi- culties of detecting interactions and moderator effects. Psychological Bulletin 114:376-90.

New Zealand Police. (1992). Post trclumcr and critical incident support for members of police. Policy circular 3 I /8/9. Un- published circular: New Zealand Police.

Norman, E. M. (1988). Post-traumatic stress disorder in


military nurses who served in Vietnam during the war years 196.5-1973. Military Medicine 154:23842.

Norris, F. H. (1990). Screening for traumatic stress: A scale for use in the general population. Journal of Applied So- cial Psychology 20:408-l 8.

Norusis, M. J. (1992). SPSS/PC+ Advanced statistics V5.0. Chicago: SPSS Inc.

Nunnally, .I. C., and Bernstein, I. H. (1994). Psychometric theory. 3d ed. New York: McGraw-Hill.

Paton, D. (1994). Dealing with traumatic incidents in the workplace. 2d ed. Queensland, Australia: Gull Publishing.

Progrebin, M. R., and Poole, E. D. (1991). Police and tragic events: The management of emotions. Journal of Crimi- nal Justice 19:395403.

Reese, .I. T., and Horn, J. M., eds. (1988). Police psychology: Operational assistance. Washington DC: U.S. De- partment of Justice, Federal Bureau of Investigation.

Solkoff, N., Gray, P., and Keill, S. (1986). Which Vietnam veterans develop posttraumatic stress disorders? Journal of Clinical Psychology 42:687-98.

Solomon, Z., and Mikulincer, M. (1990). Life events and combat-related posttraumatic stress disorder: The inter- vening role of locus of control and social support. Mili- tary Psychology 21241-56.

Solomon, Z., Mikulincer, M., and Hobfoll, S. E. (1986). Ef- fects of social support and battle intensity on loneliness and breakdown during combat. Journal of Personality and Social Psychology 5 1: 1269-76.

Solomon, Z., Mikulincer, M., and Waysman, M. (1991). Delayed and immediate onset posttraumatic stress disorder: The role of life events and social resources. Journal of Community Psychology 19:231-36.

Solomon, S. D., Smith, E. M., Robins, L. N., and Fishbach,

R. L. (1987). Social involvement as a mediator of disaster-induced stress. Journal of Applied Social Psychology 17:1092-112.

Stephens, C. and Miller, I. (1996). Traumatic experiences and posttraumatic stress disorder in the New Zealand Po- lice. Manuscript submitted for publication.

Sutker, P. B., Uddo-Crane, M., and Allain, A. N. (1991). Clinical and research assessment of posttraumatic stress disorder: A conceptual overview. Psychological Assess- ment: A Journal of Consulting and Clinical Psychology 3:52G30.

van der Kolk, B. A. (1988). The trauma spectrum: The interaction of biological and social events in the genesis of the trauma response. Journal of Traumatic Stress 1:273-90.

Violanti, J. M. (1996). Trauma, stress and police work. In Traumatic stress in critical occupations: Recognition, consequences and treatment, eds. D. Paton and J. M. Vi- olanti. Springfield, IL: Charles C. Thomas.

Vrana, S., and Lauterbach, D. (1994). Prevalence of traumatic events and post-traumatic psychological symptoms in a nonclinical sample of college students. Journal of Traumatic Stress 71289-302.

Vreven, D. L., Gudanowski, D. M., King, L. A., and King, D. W. (1995). The civilian version of the Mississippi PTSD scale: A psychometric evaluation. Journal of Traumatic Stress 8:91-109.

Weinrich, S., Hardin, S. B., and Johnson, M. (1990). Nurses respond to hurricane Hugo victims’ disaster stress. Ar- chives of Psychiatric Nursing 4: 195-205.

Williams, T. (1993). Trauma in the workplace. In Interna- tional handbook of traumatic stress syndromes, eds. J. P. Wilson and B. Raphael. New York: Plenum Press.

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