Journal of Applied Psychology 1986, Vol. 71, No. 3,484-491 Copyright 1986 by the American Psychological Association, Inc. 0021-9010/86/S00.75 A Field Experimental Test of the Moderating Effects of Growth Need Strength on Productivity George B. Graen, Terri A. Scandura, and Michael R. Graen Center for Strategic Management Studies, University of Cincinnati The literature on growth need strength (GNS) as a moderator in organizational research, particularly the job characteristics model of work motivation, is reviewed. This review reveals a preponderance of inappropriate cross-sectional surveys and few appropriate experimental tests in the field on the GNS moderator hypothesis. Next, an incremental model of growth opportunity is contrasted with that of the general level of motivating potential. It is proposed that one should manipulate growth opportunities (increments) being offered to employees in an experimental design to test GNS as a moderator in a theory of motivation. A field experiment using this approach is described. Growth opportunities were manipulated by a vertical collaboration offer based on the leader-member ex- change (LMX) model. Results of this experiment demonstrated statistically significant interaction effects between GNS and growth opportunity. As predicted, only high GNS employees responded to the growth opportunity (a 55%increase in quantity produced). This increase in quantity was not made at the expense of quality; the number of errors per week also decreased for this group. The implications of these results for future research on the moderating effects of GNS are discussed. The job characteristics model (Hackman & Lawler, 1971; Hackman & Oldham, 1976) hypothesizes that employee growth need strength (GNS) will moderate the relationship be- tween job characteristics and work outcomes. Growth needs are denned as strong needs for personal challenge and accomplish- ment, for learning, and for professional development. The model assumes that not all employees appreciate jobs high in motivating potential. Only employees having strong growth needs are predicted to develop strong internal motivation when working on complex, challenging jobs. Others, with less strong needs for growth, will be less likely to take advantage of oppor- tunities for professional development provided by a job high in motivating potential. The concept of growth need strength (GNS) is crucial to the theory of work motivation underlying the job characteristics model. At present, however, evidence regarding the validity of the growth need strength measure is inconsistent. Some studies find that the concept does operate as specified in the theory, whereas others do not (O'Conner, Rudolf, & Peters, 1980; Hackman & Oldham, 1980; White, 1978). It is not clear whether the negative findings reflect (a) a fault of the theory, (b) inadequate measurement, or (c) methodological problems. Funding for this research was supplied in part by Grant DACH 1978 6-0012 to George Graen from the Army Research Institute of the Be- havioral and Social Sciences. The authors wish to thank Joan Graen, Mike Novak, Anson Seers, Pat Sommerkamp, and Kathie Verderber for their research assistance and Ralph Katerberg for reading an earlier version of this article. The authors also wish to acknowledge the contributions of the editor and two anonymous reviewers. Requests for reprints should be sent to George B. Graen, Center for Strategic Management Studies, University of Cincinnati, Cincinnati, Ohio 45221-0020. This report describes refinements to the methods of viewing and testing the moderating effects of GNS. Tests of the Moderating Effects of GNS One purpose of this study is to clear up some of the ambiguity surrounding the moderating effects of GNS by reviewing the empirical research. Research journals publishing empirical re- ports in the areas of industrial and organizational psychology, organizational behavior, organizational theory, and personnel were searched for studies that examined the moderating effects of GNS. Only studies specifically using "growth need strength" as measured by the Job Diagnostic Survey (JDS) measures of GNS were included (either Form A, Likert format or Form B, forced choice format). The period of the search was 1971 through 1984. This period was chosen because the Hackman and Lawler (1971) study of job characteristics marks the begin- ning of the examination of GNS as a moderator of the relation- ship between the motivating potential of jobs and work out- comes. Although most of the studies reviewed assessed the job characteristics model, other studies that examined the moderat- ing effects of GNS were included. Twenty-six studies that assessed the moderating effects of GNS were located (the Champoux, 1980, article was treated as three separate studies). These studies constituted 58 tests of the moderator hypothesis (in many cases, more than one moderator hypothesis was examined in the same study). The studies were classified according to the nature of the sample, the number of subjects, and the research design em- ployed. Also, the use of Form A or Form B was recorded. In addition, the relationship hypothesized to be moderated by GNS was recorded. Finally, the empirical support for GNS as a moderator of the specified relationship was noted. The results of the literature search and classifications appear in Table 1. The studies were classified by the research design employed to 484