Acta Psychologica 36 (1972) 408416; @ North-Holland Publishing Company Not to be reproduked in any form without written permission from the publisher

THE RELATIONSHIP BETWEEN ESTIMATED PROBABILITIES

AND ACHIEVEMENT MOTIVATION 1

KLAUS SCHNEIDER

Psychologisches Institut, Ruhr-Universitiit, Bochum, Germany

ABSTRACT

Following Carnaps distinction between two ‘pre-scientific’ concepts of probability, it was predicted and found that estimated probability given in respect to one trial (‘subjective probabilityr’) is more biased by resultant achievement motivation than probability estimates given to a certain number of trials (‘subjective probabilitya’). It is contended that ambiguity facilitates motivational influences in giving probability estimates.

The proposition of MCCLELLAND et al. (1953), that relationships between achievement motivation and subjective probability exist only with ambiguous or insufficient task outcome has been confirmed within both level of aspiration (MCCLELLAND et al., 1953; KAUSLER and TRAPP, 1958) and with probability estimating procedures (BRODY, 1963; FEATHER, 1965; LITWIN, 1956). In the latter experiments Ss had to give their estimates on the bases of the task appearance or from E’s charac- terization of the task. Thus, it appears, that achievement motivation influences estimated probabilities when reality constraints on the input side are not too strong. Some years ago CARNAP (1945) distinguished two ‘pre-scientific’ concepts of probability: the first one, which he names ‘probabilityi’ means the degree of confirmation of a hypothesis and can be stated in respect to a singular event. The second probability, called ‘probabilitys’, means the relative frequency in the long run and can be stated only in respect to a series of events. Carnap states, that only a probability2 estimate can be empirical, as only such a statement can be actually tested. As reality constraints in giving a probability1

1 This paper is based on a portion of a doctoral dissertation submitted to the Abteilung ftir Philosophie, Pldagogik, Psychologie at the Ruhr-Universitat, Bochum, Germany. The author gratefully acknowledges the asisstance of Dr. Bernard Weiner and Dr. Hans-Werner Wendt in writing this paper.

408

ESTIMATED PROBABILITIES AND ACHIEVEMENT MOTIVATION 409

estimate should thus, according to Camap, be less than in giving probability2 estimate, one can predict that motivation influences come into play in a greater extent in the first case. In the relevant studies in achievement motivation research, Ss had either to estimate their chances in respect to one trial on a confidence scale (e.g. BRODY, 1963), which can be seen as an operational definition of the pre-scientific concept probability1 or in respect to a certain number of trials, as the number of hits the S believed to obtain (e.g. LITWIN, 1958), which may be a definition of the probability2 concept.2 Both kinds of subjective prob- ability are generally not distinguished in achievement motivation research, yet on the basis of Camap’s arguments one would predict that Psi estimates are more influenced by resultant achievement motiva- tion than Pss estimates.

Besides the motivational bias found in probability assessment a general bias also has been observed. When the E uses objective group norms to induce Ps, Ss always overestimated low chances of success and underestimated high probabilities (cf. FEATHER, 1966). Although Feather believed this fact to be an example of a more general principle of the relationship between objective and subjective probabilities, the marked differences make it more probable that Ss do not really accept the E’s norms. To overcome this shortcoming MOULTON (1965) first pretested his Ss and supposedly used this information to determine individuals’s subsequent chances of success. Moulton did not ascertain subjective probabilities in his experiment, so the value of his metho- dological innovation is unknown.

In the present study we shall examine the role of motivation in in- fluencing subjective probability estimates. In addition, some observations of Feather are also tested: (a) probability estimates change more after uniform success than after uniform failure; (b) success-oriented Ss show greater amount of typical change in their probability estimates after uniform success than after failure, whereas failure-oriented Ss show more revision after uniform failure. Finally, Moulton’s procedure is examined to ascertain whether supposed use of pre-test information makes subjective Ps estimates more closely related to reported norms.

* As the subject matter is subjective probabilities, following Camap they are called subjective probability1 (Pm) and subjective probabilitys (IS).

410 K. SCHNEIDW

METHOD

Subjects

Subjects were 40 male students enrolled in two high schools (12th grade) in Bochum, Germany.

Assessment of motives

Four weeks before the experiment Ss wrote stories to 6 pictures of a Thematic Aperception Test (HECKHAUSEN, 1963) under neutral condi- tions. Protocols were coded for ‘hope of success’ (HS) and ‘fear of failure’ (FF) according to the method described by HECKHAUSEN (1963) by an experienced scorer, whose coding reliability with another expert was 0.85. For every S a ‘net-hope’ score (NH) was then calculated by subtracting FF from HS. Ss were classified as high (NH > 0) and low (NH < 0) in resultant achievement motivation.

Procedure

Ss were tested individually in the two institutions. The experimental task was a digit symbol task which consisted of the digits l-6 and the symbols: Y, k, Z, V, 0, r. Each S received a stack of cards, each card containing four rows of either sixteen or seventeen digits. The S first was pretested with a similar task (the digit symbol task of the Wechsler Adult Scale), and told that with this information his chances of success in the following trials of the task could be predicted (see MOULTON, 1965). Ss were then informed that they had to complete all the substitutions on each of the following cards within an allotted time period, which was varied for every S as a function of his performance in the pretest. There were two conditions, a success and a failure condition. In the success condition (condition A) the S was told that the task was relatively easy and that his individual chances of success were 90 successes in 100 trials. In the failure condition (condition B) he was told that the task was relatively difficult and that his chances were only 10 successes in 100 trials. Ss in condition A received first five successes and one failure; Ss in condition B received first five failures and one success. The single success or failure was alternatively administered at trial 4 or 5. After trial 6 the feedback direction was reversed, Ss in condition A got uniform failure, those in condition B uniform success feedback. In a failure trial the S was interrupted after completing about 64 symbols, which corresponded to the number of symbols completed

EsTlbUTED PROBABILITIES AND AC- MOTIVATION 411

in a success trial. The stop varied between the digits 62 and 66 so as not to make the Ss suspicious of the deceit. Prior to each trial Ss estimated their probabilities of success for: (a) the next trial on a 100 % confidence scale divided in equal steps of ten (PSI); (b) the number of successes S expected to have on the next ten trials, on a scale from 0 to 10 (Pss).

REWLTS

Mean probability estimates before all trials are shown in figs. 1 and 2. All estimates are transformed into decimal fractions. Every point in figs. 1 and 2 represents the mean estimate of 10 Ss. Estimates of both kinds of Ps before trial 1 in the easy condition A differ from those of the difficult condition B (main effect ‘condition’, Pa: F(l/36) = 14,80, p < 0.01; Pss : F(l/36) = 27,83, p < 0.01). Differences between success- and failure-oriented Ss before trial 1 are only found with Psi estimates in condition B, where Ss have been told that the task is difficult (main effect ‘motivation’: F(1/36) = 6,79, p < 0.05; interaction ‘condi- tion x motivation’: F(1/36) = 4,11,p < 0.05; simple effects for ‘motiva- tion’ : condition A: F(l/36) = < 1; condition B: F(l/36) = 10,73, p < 0.01). In respect to Pss estimates, where reality constraints were believed to be greater, the main estimates do not differ between the motivation groups (main effect and interaction: F < 1).

- HS,FF (Cord Al - FFWS l&d Al - HS>FF lcond El b-0 FFWS Gad 8j

I I I I I1 I I III III I I

1 2345670 9 w 11 12 13 14 15 16 TRIALS

Fig. 1. Mean estimates of PSI made by success and failure. oriented Ss in condition A and B over all trials.

412 K. SCHNEIDER

Figs. 1 and 2 also show that Ss revise their estimates in the first 7 trials and also in the following ones as a function of actual task out- come. Thus separate analyses of variance for PSI and Pss estimates show besides a significant main effect for ‘condition’ with both kinds of estimates (PSI : F(1/36) = 6,48, p < 0.05; Pss : F(1/36) = 14,69, p < 0.01) significant interactions ‘condition x trial’ (PSI : F(15/540) =

- HS>FF ICond Al - FF>HS ICeadA) - HS,FF ICond BI - FFBHS (Cond 81

11 11 11 11 11 11 11 11 I

1 2 3 4 5 6 7 8 9 n 11 12 13 14 15 f TRIALS

Fig. 2. Mean estimates of Pss made by success and failure oriented Ss in condition A and B over all trials.

44,27, p < 0.001; Pss: F(15/540) = 38,63, p < 0.001). The differences between Ss are significant with both kinds of estimates (PSI : F(39/540) =

38,98, p < 0.001; Pss: F(39/540) = 29,22, p < 0.001). There also remain marked differences in mean PSI estimates between success- and failure-oriented Ss in condition B. Although the effect for ‘motivation’ over all trials is only of borderline significance in the whole group (F(1/36) = 3,66, p < 0.07), it remains significant in condition B (F(1/36) = 4,69, p < 0.05). As fig. 1 shows, these differences decrease with increasing task experience. Thus there are no differences between success- and failure-oriented Ss in the last trial. Also the trend analysis for PSI estimates shows significant interactions ‘motivation x trial’ (F(15/540) = 2,20, p < 0.01) and ‘condition x motivation x trial’ (F(15/540) = 3,63, p < 0.01).

ESTIMATED PROBABILITIES AND ACHIEVEMENT MOTIVATION 413

Revision scores

For the first 4 trials, where uniform success (condition A) or uniform failure (condition B) was administered, a revision score was determined. A final score was considered the mean of three revisions from trial l-2, 2-3, and 34. Revisions were given a positive sign if they were in the ‘typical direction’, i.e. upwards after success and down after failure. Fig. 3 presents these revision scores. It is apparent that there is greater revision after success than after failure, @‘(l/36) = 4,48, p < 0.05). Further there is a trend for success-oriented Ss to revise these scores more in both conditions @(l/36) = 2,46, p < 0.25) than failure- oriented Ss. All other effects are negligible.

.07 -

2 .06- 8 2 .05 -

6 2

.04 -

$ .03-

a

g

.02-

.Ol -

L

ps2

A / A B success failure success failure

Fig. 3. Mean revision scores of estimated probability between trials l-2, 2-3, 34, respectively, of success and failure oriented Ss in a success and failure condition.

The fact that these revision scores are not independent from achieve- ment motivation can be demonstrated by a correlation analysis. Table 1 shows the correlations between ‘hope of success’ (HS), ‘fear of failure’ (FF) and the revision scores. The revision scores were not independent from estimates before trial 1. Therefore, estimates before trial 1 were held constant by calculating partial corre1ations.s

HS is positively related to the amount of typical revision in both conditions, although the correlation is statistically significant only in

* In contrast to CRANDALL et al. (1964) we believe these effects to be just floor and ceiling effects.

414 K. SCHNEIDER

TABLE 1 Partial correlation coefficients between HS, FF and probability revision scores after

uniform success (condition A) and uniform failure (condition B) (n = 20).

Condition A (success) Condition B (failure)

PSl Psa Psi Psa

HS 0.327 0.555, 0.247 0.283 FF 0.068 - 0.349 - 0.231 - 0.417

* p< 0.01, one-tailed.

the success condition and only with PSZ estimates. FF is negatively related to revision scores in both conditions. The relation is not statisti- cally significant.

DISCUSSION

The main hypothesis was confirmed: only PSI estimates, which are more ambiguous, are influenced by resultant achievement motivation. Also the Ps estimates differences diminish with later trials, as more feedback has been received. This had been hypothesized and confirms the results of MCCLELLAND et al. (1953), KAUSLJB and TRAPP (1958) and FEATHER (1965). Thus we conclude that ambiguity will facilitate the influence of motivational factors on the giving of Ps estimates. This holds both, when the information given is ambiguous, and also when the estimates are ambiguous. That the marked differences between success oriented Ss and failure oriented ones were found only in the low Ps condition, resembles a finding reported by FEATHER (1965). It may be explained either with Feather’s generalization hypothesis - success oriented Ss have experienced more successes with tasks of low and medium difficulty in their past than failure oriented Ss - or with IRVIN’S (1953) hypothesis of non-independence between the valence of an outcome and stated probability. According to ATKINSON (1964) the success valence must be bigger for success-oriented Ss than for failure oriented ones.

Mean Ps estimates before trial 1 show that also with Moulton’s technique of pretesting Ss and telling them their individual chances, Ss believe their chance to be more in the medium range than they have been told. Moulton’s technique as well as the often used procedure of giving objective group norms do apparently not ensure, that Ss

ESTIMATJ3D PROBABILITIES AND ACHIEWMEN T MOTIVATION 415

don’t give theirestimates according to a ‘principle of unsufficient reason’ before having got any real feedback.

The finding that revision of probability is more marked upwards after success than downwards after failure is contrary to our hypothesis and contradicts earlier findings (cf. FEATHER, 1968). Also in opposition to our hypothesis there was positive relationship between HS and ‘typical’ revision as well after success as after failure and negative ones with FF. Yet only the positive relationship between HS and upward revision after success is significant, when estimates before trial 1 are held constant by partial correlation. Thus Feather’s assumption of a positive relationship between HS and typical recision after success as well as of a positive one between FF and typical revision after failure is only partially confirmed.

(Accepted April 27, 1972.)

REFBRENCE.¶

ATKINSON, J. W., 1964. An introduction to motivation. Princeton: Van Nostrand. BRODY, N. N., 1963. N achievement, test anxiety and subjective probability of success

in risk-taking behavior. Journal of Abnormal and Social PsychoIogy 66, 413418.

CARNAP, R., 1944-1945. The two concepts of probability. Philosophy and Pheno- menological Research 5, 5 13-532.

CRANLMLL, V. C., S. GOOD and V. J. WALL, 1964. Reinforcement effects of adult reactions and non-reactions on children’s achievement expectations; A replication study. Child Development 35, 485-497.

FEATHER, N. T., 1965. The relationship of expectation of success to need achievement and test anxiety. Journal of Personality and Social Psychology 1, 118-126.

FEATHER, N. T., 1966. Effects of prior success and failure on expectations of success and subsequent performance. Journal of Personality and Social Psycho logy 3, 287-298.

FEATHER, N. T., 1968. Change in confidence following success or failure as a predictor of subsequent performance. Journal of Personality and Social Psychology 9, 38-46.

HECKHAUSEN, H., 1963. Hojiuutg und Furcht in der Leistungsmotivation. Meisenheim: Hain.

IRWIN, F. W., 1953. Stated expectations as functions of probability and desirability of outcomes. Journal of Personality 21, 329-335.

KAUSLER, D. H. and E. P. TRMP, 1958. Achievement motivation and goalsetting behavior on a learning task. Journal of Experimental Psychology 55,575-578.

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Lrrwr~, G. H., 1958. Motives and expectancy as determinants of preference for degree of risk. Unpubl. honors thesis, Univ. of Michigan. In: J. W. Atkinson and N. T. Feather (eds.), A theory ofachievement motivation. New York: Wiley, 1966.

MCCLELLAND, D. C., J. W. ATKINSON, R. A. CLARK and E. L. LOWELL, 1953. The achievement motive. New York: Appleton-Century-Crofts.

MOULTON, R. W., 1969. Effects of success and failure on level of aspiration as related to achievement motives. Journal of Personality and Social Psychology 1,

399406.