The Effects of Group Versus Individual Goal Setting on

The Sport Psychologist, 1997,11,190-200
O 1997 Human Kinetics Publishers. Inc.
The Effects of Group Versus Individual Goal
Setting on Bowling Performance
Scott R. Johnson, Andrew C. Ostrow,
Frank M. Perna, and Edward F. Etzel
West Virginia University
The purpose of this study was to examine the effects of group and individual
goal setting versus a control condition on bowling performance (BP), personal
goals (PG), and perceived goal difficulty (PGD) across five weeks. Novice
bowlers (N = 36) were randomly assigned to one of the three goal conditions.
Three separate 3 X 5 (Goal Condition X Time: Weeks of Study) repeated
measures analysis of variance (ANOVA) revealed significant main effects for
time on BP and PGD, and significant group by time interaction effects on BP
and PG. The significant group X time interaction effects revealed that participants in the group goal setting condition increased both BP and PC relatively
more than participants in the other goal setting conditions. Therefore,
group goal setting may enhance performance in an individual sport by
potentially increasing personal goal setting under difficult performance
demands.
Key Words:Group Goal Setting, Individual Goal Setting, Bowling Performance
Many motivational techniques have been used by coaches and physical educators to improve the performance levels of athletes. One method that both researchers and practitioners have found effective in eliciting commitment, perseverance, dedication, and effort required for long-term self-motivation is goal setting
(Silva & Weinberg, 1984). Goal setting investigations also have supported the
effectiveness of establishing individual goals in order to enhance performance
(Burton, 1989; Weinberg, Bruya, Longino, & Jackson, 1988).
Contemporary literature in sport, physical activity, and industry suggests
that goal setting has a beneficial effect on motivation and subsequent performance
(Boyce, 1992; Burton, 1989), and individual goal setting has been the primary
focus of research (Brawley, Carron, & Widmeyer, 1992).However, the use of group
Scott R. Johnson, Andrew C. Ostrow, Frank M. Perna, and Edward F. Etzel are all
with the Sport Behavior program, School of Physical Education at West Virginia University, Morgantown, WV 26506-61 16.
Group and Individual Goal Setting
191
goal setting alone, and in comparison to individual goal setting, has gained increased attention in the sport domain (Frierman & Gill, 1994; Lee, 1988; Locke,
1991). In support of the potential benefits of group goal setting in the sport domain, Locke and Latham (1985) stated that similar positive results occur from
both individual and group goal setting. Brawley and his colleagues (1992) also
have suggested that research should examine the mechanisms operating in group
goal setting interventionsand compare the effectiveness of group versus individual
goal setting procedures.
Since Locke and Latham's (1985) review, several studies have attempted
to document the effectiveness and elucidate the potential mechanisms (i.e.,
self-efficacy and team cohesion) underlying the efficacy of group goal setting in
the sport domain. Lee (1988) examined women's field hockey teams in order to
investigate the relationship among team goals, self-efficacy,and actual team performance. Lee (1988) reported that team goals were significantly positively related to planning and team winning percentage, and team goals accounted for
more of the variance in winning percentage than did self-efficacy. Based on the
relative amount of variance in winning percentage accounted for by team goals
and self-efficacy, Lee (1988) suggested that self-efficacy may mediate the effect
of team goals on team performance. Moreover, the finding that both team goals
and self-efficacy remained significant in a model predicting winning percentage
indicates that setting team goals exerted an independent effect on winning percentage. Therefore, while one possible benefit of setting team goals may be that
of increasing self-efficacy or personal goals which in turn may lead to performance increase, Lee's (1988) nonexperimental design could not adequately test
for the presence of a mediating effect. The design also did not account for potential effects of personal goals, which are known to influence goal setting efficacy
(Locke, 1991).
Goal setting also may influence team cohesion. Cox (1990) has suggested
that group goal setting may facilitate increased cohesion and motivation of individuals to work toward a common goal which may obviously benefit team sports
such as football and basketball. However, Cox (1990) has also suggested that
group goal setting may be as effective as individual goal setting in coactive sports
where team success is dependent on the aggregate performance of individuals
who perform independently (e.g., bowling, track, and tennis teams). In a 10week study comparing the effects of group versus individual goal setting on
bowling league winning percentage and team cohesion, Frierman and Gill (1994)
found that individual and group goal setting interventions were equally more
effective than a "do your best" control condition. However, there were no significant [sic] between group differences in team bowling average or on either
task or social cohesion, indicating that team cohesion could not mediate the effect of goal setting intervention on bowling performance (Frierman & Gill, 1994).
Additionally, while Frierman and Gill's (1994) results support the potential use
of group goal setting, it is difficult to assess the relative efficacy of group goal
setting to improve individual performance because individual bowling scores
were not reported.
As we have reviewed, goal setting studies in the sport domain have not adequately compared goal setting format (e.g., group and individual), nor has the
potential effect of goal setting format on personal goals been explored. Measuring
personal goals is desirable in order to determine if participants have accepted their
a
192
Johnson, Ostrow,Perna, and Etzel
goals which in turn are thought to influence subsequent effort (Locke, 1991). We
would also add that no sport setting study has assessed perceived goal difficulty.
Because moderately difficult goals generally produce better performances than
relatively less or extremely difficult goals (Locke & Latham, 1984), it is important
to assure that goal setting participants are equated on perceived goal difficulty
prior to a goal setting intervention. Similarly, perceived goal difficulty should be
known in order to assess if task difficulty produces a main effect or interacts with
goal setting format on task performance (Locke, 1968). For example, after initially assuring that participants had sufficient ability to perform a task, Locke (1968)
found that perceived goal difficulty moderated the relationship between goal setting and task performance. Exploring relationships among goal setting format,
personal goals, and perceived goal difficulty in an experimental design may also
elucidate the requisite conditions and potential mechanisms underlying the effectiveness of goal setting.
The purpose of the present study was to examine the effect of goal setting
format (individual, group, "do your best") on BP, PG, and PGD in a five-week
experimental design consisting of baseline, intervention, and retention phases. Based
on the extant literature, equating the efficacy of group and individual goal setting,
and the relative lack of data regarding potential mechanisms, we hypothesized that
both group and individual goal setting would similarly increase PG and individual
BP scores to a greater degree than a "do your best" condition. Because bowling is
a learned coactive skill, we also hypothesized that BP increase would be retained
after formally removing the goal setting intervention. A secondary aim was to
clarify the interrelationship among BP, PG, and PGD. We hypothesized that participants would perceive the bowling task as difficult throughout the study and that
PG would be positively related to BP.
Method
Participants
Thirty-six male undergraduate students (mean age = 21.6 years), enrolled in two
beginning level bowling classes at a large Midwestern university, volunteered to
participate in this research investigation. This study was initiated after all participants completed an eight-week instructional bowling program in which fundamental skills were introduced. The same bowling instructor taught both classes.
Permission from the Institutional Review Board for the Protection of Human Subjects was granted prior to the commencement of this study.
Procedure
Participants were categorized into one of three bowling ability levels (i.e., high,
medium, low) based on four baseline bowling performance scores (i.e., number of
pins knocked down). Six three-member teams per class were then constructed by
randomly assigning a bowler from each ability level to each bowling team. Each
team was then randomly assigned to one of the three conditions (i.e., group goal
condition, individual goal condition, or "do your best" group).
All participants bowled two games on two different days per week across
five weeks. Participants bowled four games during the baseline phase, 12 games
during the intervention phase (i.e., three weeks), and four games during the retention
Group and Individual Goal Setting
193
phase, respectively. During the intervention phase, participants in the goal intervention groups also completed measures of PG and PGD. In order to minimize the
extent of personal goal setting in the "do your best" group, these participants did
not complete the PG and PGD measures, and they were simply told to "do your
best" throughout the entire study.
Goal Setting Interventions
O'Block and Evans (1984) developed a computational procedure called "Interval
Goal Setting" (IGS) as a guide for setting performance goals for events that are
measured with standard, quantitative scores (Silva & Weinberg, 1984). The IGS
model is composed of six steps that uses previous performance measures to provide a realistic range for the next goal (O'Block & Evans, 1984). The four baseline
scores were used to calculate participants' initial bowling average and bowling
goal. O'Block and Evans (1984) maintained that this procedure can remove the
subjectiveness from goal setting and enhances overall performance.
During the intervention phase, both goal intervention groups received instructions on IGS. In addition, the principal investigator explained the importance
of goal setting in sport performance and guidelines for setting realistic goals. In a
5-minute meeting prior to each bowling session, participants in the group goal
condition received only their group goals via the IGS procedure, whereas participants in the individual goal condition received their individual goals via the IGS
procedure. The "do your best" group did not receive any goals and were asked to
"do their best7' before each bowling session. In contrast to the individual goal
condition, participants in the group goal condition attempted to bowl an overall
team score for each game. The team goal was established by inserting each team
member's score into the IGS model and then computing an average score. After
each bowling session (i.e., two games) in the intervention phase, participants' bowling scores in both goal intervention groups were inserted into the IGS model to
establish a new goal for the next bowling session for each intervention group.
Because the teams were comprised of bowlers of similar ability, the IGSderived goals at the beginning of the intervention should not produce significantly
different goals for bowlers assigned to the individual and group goal setting conditions. However, as actual performance changes across goal setting conditions, IGS
goals would naturally fluctuate accordingly. During the one-week retention phase,
participants in both goal intervention groups were not assigned an IGS goal.
Dependent Variables
Bowling Pegormance. Weekly bowling performance was defined as the
number of pins knocked down per official 10-frame game and averaged across
four games.
Personal Goals. Prior to receiving their IGS goals, participants in both
goal intervention groups reported their personal goal (i.e., "During today's bowling session, how many bowling pins do you want to knock down per game?") for
the upcoming bowling session. Participants in the group goal setting condition
anonymously wrote down their personal goals for the team and discussed the IGS
goal in a team format. Participants in the individual goal group also anonymously
wrote their personal goals for their individual bowling performance and were told
not to discuss their personal goals with their teammates.
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Johnson, O s f r m ,Perna, and Etzel
Perceived Goal Difficulty. Prior to receiving their IGS goal for the day,
participants assigned to both goal intervention groups were asked "How easy or
difficult do you perceive the assigned Interval Goal in relation to your personal
goal?" for either your team (i.e., group goal condition) or for yourself (i.e., individual goal condition), respectively. The goal difficulty item was rated on a 5point ordinal scale ranging from (1) "extremely easy to achieve" to (5) "extremely
difficult to achieve."
Results
Preliminary Analysis
While participants from each class were randomly assigned to intervention groups,
with small sample sizes it was possible that intervention groups may have, nonetheless, differed on initial bowling ability (Champion, 1981). A three-way ANOVA
(Class X Bowling Ability X Intervention Group) was employed in order to confirm that differences in bowling ability were similarly distributed among intervention
groups and the two bowling classes at baseline. Results indicated that no main
effects existed for class, F (1, 17) = 1.48, p > .05 or intervention group
F (2, 17) = .13, p > .05, nor were there significant interaction effects, ps > .05.
However, as expected, a main effect for bowling ability was observed,
F (2, 17) = 34.31, p < .01. A linear contrast indicated that participants were successfully categorized as high (M = 144.73, SD = 11.44), medium (M = 124.54,
SD = 3-51), and low (M = 113.83; SD = 4.13) on bowling ability,
F (1, 17) = 107.10, p < .01. Further preliminary analyses showed that the IGSsystem yielded similar goals for participants assigned to the group
(M = 169.65, SD = 15.24) and individual (M = 172.79, SD = 21.23) goal setting
conditions at the start of the intervention, t (22) = .42, p > .05. The similarity of IGS
goals between conditions at baseline indicated that the IGS-system did not yield relatively easier or harder goals across groups.
The Effects of the Interuentions on Bowling Performance
BP means and standard deviations of the three intervention groups across the three
phases of the study are presented in Table 1. A 3 X 5 (Goal Condition X Time:
Weeks of Study) ANOVA, with repeated measures on the last factor, compared the
average BP of the three intervention groups across the study. No main effect existed
for intervention group, F (2, 33) = 1.94, p > .05. However, a main effect across
weeks was observed, F (4, 132) = 3.72, p < .05, as was a statistically significant
interaction effect, F (8, 132) = 2 . 3 8 , ~< .05. In this statistical analysis, the interaction effect was of most interest because the obtained F-ratio indicated the relative
change in BP among the three groups across the five weeks of the investigation.
Planned orthogonal contrasts clarified the nature of the interaction effect by
specifying the pattern of BP changes over time within each group (Rosenthal &
Rosnow, 1985). Quadratic contrasts were used to determine if bowling scores increased and then plateaued over time. A significant quadratic contrast was found
only for the group goal setting condition, F (1, 11) = 6.40, p < .05, respectively
(see Figure 1). These results indicated BP increased over the intervention phase
(Weeks 2 to 4) for participants in the group goal condition, and that BP increase
was retained during the retention phase (Week 5) (see Figure 1). No statistically
Group and Individual Goal Setting
195
Table 1 Bowling Performance Scores of Goal Conditions Over a Five-Week Period
Goal conditions
Group
Individual
"Do Your Best"
WEEK 1 (Baseline Phase)
Mean score
Standard deviation
WEEK 2 (InterventionPhase)
Mean score
Standard deviation
WEEK 3 (InterventionPhase)
Mean score
Standard deviation
WEEK 4 (InterventionPhase)
Mean score
Standard deviation
WEEK 5 (Retention Phase)
Mean score
Standard deviation
significant contrasts were found for either the individual or "do your best" goal
group scores.
Personal Goals
The means for participants' PG in both goal intervention groups across the intervention phase are displayed in Figure 2. A 2 X 3 (Intervention Group X Time:
Weeks During Intervention Phase) ANOVA, with repeated measures on the last
factor, was employed in order to assess personal goal differences between participants in the two goal setting conditions across the intervention phase. The analysis
revealed that no main effects existed for goal intervention group, F (1,22) = .41,
p > .05, or time, F (2, 44) = 3.06, p > .05. However, a significant group X time
interaction effect was observed, F (2,44) = 8.55, p < .01. Planned contrasts revealed that PG increased linearly over the intervention phase for participants in
the group goal setting condition, F (1, 11) = 4.61, p < .01. The linear increase in
PG indicated that PG continued to increase throughout both interventions. However, PG did not change significantly for participants in the individual goal setting
condition, F (1, 11) = 1.04, p > .05.
Perceived Goal Difficulty
The means for participants' PGD in both goal intervention groups are also presented in Figure 2. A 2 X 3 (Intervention Group X Time: Weeks During Intervention Phase) ANOVA, with repeated measures on the last factor, was conducted in
order to examine PGD between the two goal setting conditions during the intervention phase. The analysis revealed a significant main effect for time
F (2,44) = 3.39, p < .05. However, there was no main effect for goal intervention
group, F (1, 22) = . I 1, p > .05, nor a significant interaction effect between goal
196
Johnson, Ostrozu, Perna, and Etzel
t
- 011
Week I
Figure 1-Team
-
I
"O
Week 3
Week 2
Group
Individual
Do Your Best
Week 4
Week 5
bowling performance means across the five-week study.
170
-
165 -
160
-
Group
Individual
-
Week 2
Group
Individual
I
I
Week 3
Week 4
Intervention Phase
Figure %Personal goal means and perceived goal difficulty means for the goal intervention groups.
Group and Individual Goal Setting
197
intervention group and PGD across time, F (2, 44) = .58, p > .05. A follow-up
contrast indicated that PGD increased linearly over time for both groups
F (1,22) = 5.23, p < .05.
Relationships Among Goal Difficulty, Personal Goals, and
Bowling Petformance
In order to assess group differences in actual goal difficulty, we computed the
average weekly difference between actual BP and the IGS goals for each participant. Ninety-five percent of participants never achieved their IGS goals. A repeated measures ANOVA compared the mean BP-IGS differences between goal
intervention groups across the intervention phase. This revealed a nonsignificant
group effect, F (1, 22) = .01, p > .05, and no time or group X time interaction
effects, F s (2,44) = 1.14 and .77, respectively, ps > .05.
A Pearson-Product Moment correlation coefficient was computed in order
to analyze the relationship between the average personal goal and averaged team
bowling scores for both goal intervention groups at the end of the intervention
phase. Participants setting relatively higher PG had relatively greater BP, r (24) = .5 1,
p < .05. A partial correlation coefficient further indicated that the significant relationship between PG and BP remained for the final week of intervention after
controlling for initial bowling ability, r = .43, p < .05. However, there was little
relationship between participants' averaged PGD and BP, r = .08,p > .05, suggesting that perceived difficulty was unrelated to actual performance.
Discussion
The primary purposes of this investigation were to experimentally examine the
effects of group and individual goal setting interventions versus a "do your best"
condition on team bowling performance and to examine the relationship among
BP, PG, and PGD. Our results only partially supported our primary research hypotheses. Specifically, we found that participants assigned to the group goal setting intervention significantly improved their mean personal BP and maintained
their performance increase, but individual goal setting and "do your best" participants did not improve across the five-week study. Additionally, group goal setting
participants also set more difficult personal goals in comparison to the individual
group, and PG was ~ i ~ c a n tcorrelated
ly
with subsequent BP even after accounting
for initial ability. The increase in PGD throughout the study and the discrepancy
between the IGS-goal and actual bowling score among all participants indicated
that participants experienced the bowling task as being similarly difficult.
The results of our study provide partial support for Locke and Latham's
(1985) statement that team goal setting may produce the same positive results that
are found in individual goal setting tasks. In other words, a specific, difficult, and
challenging goal, whether it is an individual or team goal, can enhance performance more than a goal that is vague, unclear, and nonchallenging. However, in
the present study, individual goal setting was no more effective in improving BP
than a control condition. While bowling performance was specific, quantifiable,
and fully controllable by the participants, one factor that may partially account for
the ineffectiveness of individual goal setting could be bowling task difficulty as
indexed by PGD rating and the IGS system. High PGD ratings, regarding the
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Johnson, Ostrow,Perna, and Etzel
difficulty of meeting the IGS system-derived goals and the finding that 95% of
participants never achieved the IGS goal, suggests that the IGS-derived goal may
have been too difficult. Therefore, it possible that whereas challenging goals may
lead to performance increases, overly difficult goals may negatively impact success expectancy and effort (Locke & Latham, 1985 ).
However, it is of interest to find that group goal setting improved BP as well
as BP expectancy (e.g., personal goals) under highly challenging conditions (difficult IGS-goals). It is also important to note that actual task difficulty, as defined by
the IGS goal and PGD ratings, was not significantly different between goal setting
groups at any time point. Hence, it was not simply the case that participants in the
group goal setting condition had a higher IGS-goal or perceived the task as harder
or easier than the individual goal setting group. It is possible that group goal setting facilitated elements of the social environment that may have contributed toward the group goal setting participants establishing higher personal goals and
persisting under difficult performance demands (Jackson &Williams, 1985;Zajonc,
1965).For example, Jackson and Williams (1985) found that participants performed
better individually on simple cognitive tasks, but on difficult tasks, being in groups
facilitated individual performance. Whereas bowling is a motor task, successful
performance is largely dependent on skill execution involving cognitive
decision-making components.
While another possible social facilitation effect, decreased perceived task
difficulty in the presence of others, did not appear to be operative in our study,
future investigations may seek to explore other social phenomenon that may elucidate the potential mechanism underpinning the efficacy of group goal setting. For
example, we did not formally assess various forms of social support (i.e., instrumental and emotional), task planning activity or other coping strategies that previously have been identified as potentially useful in stressful situations (Carver,
Scheier, & Weintraub, 1989; Crocker &Thomas, 1996).However, we did observe
that each team in the group goal condition purposely assigned a lead-off bowler.
Bowlers in the group goal setting condition usually communicated with their teammates and provided encouragement and technical feedback in relation to achieving the team performance goal. Team members who work together toward a common goal may form a stronger cooperative unit (Sherif & Sherif, 1953), and
cooperation has been found to promote higher achievement in terms of quality,
accuracy, and speed of performance than independent or individualistic work across
a variety of tasks (Johnson & Johnson, 1985). It should also be noted that possible
group facilitation effects on individual performance are conceptually distinct from
task and social team cohesion factors that have not been found to be differentially
altered by individual and group goal setting (Frierman & Gill, 1994).
Another possible explanation pertaining to the higher mean bowling scores
within the group intervention condition as compared to the individual and "do
your best" groups across the study may be couched in goal perspective theory. The
goal perspective theory states that personal goals influence how people think, feel,
and act in achievement situations (e.g., sport) (Duda, Chi, Newton, Walling, &
Catley, 1995). In support of goal perspective theory, Theodorakis (1995) demonstrated by use of path analysis that performance improvements are a direct result
of increased personal goals. In the present study, PG only increased for participants in the group goal setting condition and PG were positively correlated with
BP. However, the mechanisms by which group goal setting may facilitate personal
goal setting is currently unknown.
Group and Individual Goal Setting
199
A final consideration related to participant improvement in the group goal
condition is that the group goal was, in reality, a public goal. Participants in the
group goal condition were aware of both the team's IGS goal and the team's personal goal before the start of each bowling session. In the individual goal condition, the IGS goal and the personal goal for each participant was not explicitly
made public to other teammates. Publicly stating goals is known to increase commitment and subsequent performance (Locke & Latham, 1985). It is also possible
that making the goal public in the group.goa1 condition may have facilitated commitment and performance to a greater degree than in the individual goal setting
condition. Because our design did not include objective measures or codified behavioral observations of communication frequency and quality, we could not empirically determine if discussion varied between goal setting conditions. Facilitation of discussion may represent another possible mechanism underpinning the
efficacy of group goal setting that future investigations may pursue.
h summary, our data suggests that group goal setting is effective in improving individual performance and increasing personal goals in a coactive sport. However, the extent to which we may generalize our findings may be limited to highly
difficult tasks. Replication of our study with a modified version of the IGS system
may clarify if group goal setting efficacy is influenced by task difficulty. Additionally, behavioral and general measures of group cooperation and coping may further our understanding of the effects and mechanisms of group goal setting on
performance outcomes.
References
Brawley, L.R., Carron, A.V., & Widmeyer, W.N. (1992). The nature of group goals in sport
teams: A phenomenological analysis. The Sport Psychologist, 6,323-333.
Boyce, B.A. (1992). The effects of goal proximity on skill acquisition and retention of
shooting task in field-based setting. Journal of Sport and Exercise Psychology, 24,
298-308.
Burton, D. (1989). The impact of goal specificity and task complexity on basketball skill
development. The Sport Psychologist, 3,34-47.
Carver, C.S., Scheier,M.F., & Weintraub, J.K. (1989).Assessing coping strategies:A theoretically based approach. Journal of Personality and Social Psychology, 56,267-283.
Champion, D.J. (1981). Basic statistics for social research (2nd ed.) New York: Macmillan
Publishing Co., Inc.
Cox, R.H. (1990). Sport psychology: Concepts and applications (2nd ed.) Dubuque, IA:
Wm. C. Brown Publishers.
Crocker,P., &Thomas,T.R. (1996). Coping by competitive athletes with performance stress:
Gender differences and relationships with affect. The Sport Psychologist, 9, 325338.
Duda, J.L., Chi, L., Newton, M.L., Walling, M.D., & Catley, D. (1995). Task and ego orientation and intrinsic motivation in sport. International Journal of Sport Psychology,
26,40-63.
Frierman, S.H., & Gill, D. (1994).The influence of individual and team goals on cohesion
and performance in youth bowling. Journal of Sport and Exercise Psychology, 16,
(Suppl. l), S54.
Jackson, J.M., & Williams, K.D. (1985). Social loafing on difficult tasks: Working collectively can improve performance. Journal of Personality and Social Psychology, 49,
937-942.
200
Johnson,Osfrow,Perna, and Etzel
Johnson, D.W., & Johnson, R.T. (1985). Motivational processes in cooperative, competitive, and individualistic learning situations. In C. Ames & R. Ames (Eds.), Research
on motivation in education (Vol. 2, pp. 249-289). Orlando, FL: Academic Press.
Lee, C. (1988). The relationshipbetween goal setting, self-efficacy, and female field hockey
team performance. International Journal of Sport Psychology, 20,147-161.
Locke, E.A. (1968). Toward a theory of task motivation incentives. OrganizationalBehavior and Human Performance, 3,157-189.
Locke, E.A. (1991). Problems with goal-setting in sports-and their solutions. Journal of
Sport and Exercise Psychology, 8,311-316.
Locke, E.A., & Latham, G.P. (1984). Goal setting: A motivational technique that works.
Englewood Cliffs, NJ: Prentice-Hall, Inc.
Locke, E.A., & Latham, G.P. (1985). The application of goal setting to sports. Journal of
Sport Psychology, 7,205-222.
O'Block, F.R., & Evans, F.H. (1984). Goal setting as a motivational technique. In J.M.
Silva 111& R.S. Weinberg (Eds.), Psychologicalfoundations of sport (pp. 188-196).
Champaign, IL: Human Kinetics.
Rosenthal, R., & Rosnow, R.L. (1985). Contrast analysis: Focused comparisons in the
analysis variance. Cambridge, MA: Cambridge University Press.
Sherif, F., & Sherif, 0. (1953). Groups in harmony and tension. New York Harper.
Silva 111, J.M., & Weinberg, R.S. (1984). Psychological foundations of sport. Champaign,
IL: Human Kinetics.
Theodorakis, Y. (1995). Effects of self-efficacy, satisfaction, and personal goals on swimming performance. The Sport Psychologist, 9,245-253.
Weinberg, R., Bruya, L.. Longino, J., & Jackson, A. (1988). Effect of goal proximity and
specificity on endurance performance of primary children. Journal of Sport and Exercise Psychology, 10,81-91.
Zajonc, R.B. (1965). Social facilitation. Science, 149,269-274.