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Effects of time of day and personality on intelligence test scores
Person. individ. 01% Vol. 12, No.
11.pp. 1227-1231,
0191~8869/91$3.00+ 0.00 Copyright 0 1991Pergamon Press plc
1991
Printed in Great Britain. All rights reserved
EFFECTS OF TIME OF DAY AND PERSONALITY ON INTELLIGENCE TEST SCORES SUNITA GUPTA Department of Psychology, Guru Nanak Dev University, Amritsar-143005, India (Received
I6 November
I990; accepted for publication
27 March IWI)
Summary-The present investigation was designed to study the time of day effects on intelligence test performance in subjects varying on extraversion and neuroticism dimensions of personality according to a procedure known as ‘zone analysis’. A factorial design involving four levels of personality and three day timings with repeated measures on the second factor was replicated 15 times. Cattell’s Culture Fair Intelligence Test (CFIT), Scale III, Form A served as the criterion measure. The study supports the following conclusions: (1) the performance on the CFIT was better in the evening (1900 hours) than in the morning(0900 hours) and afternoon (1400 hours) except for topology subtest; (2) personality did not produce any effect on CFIT performance; (3) personality and time of day did not interact in their effects on CFIT performance.
INTRODUCTION
Attributing individual differences in personality to the presence of differences in the levels of activity in the cortico reticular loop, Eysenck (1967a) postulates that introverts have a chronically higher level of cortical arousal than extraverts. But human circadian rhythms also play an important role in individual differences. Blake (1967) reports that introverts are more aroused than extraverts only at certain times of the day. Thus people who prefer to work in the morning may be called ‘morning types’ and those who prefer to work in the evening may be called ‘evening types’. Horne and Ostberg (1976) and Horne, Brass and Pettitt (1980) report that morning types show a rapid rise in body temperature during the morning and reach their peak body temperature earlier than evening types. Introverts tend to be ‘morning types’ with higher body temperature in the morning than extraverts, the ‘evening types’ (Blake, 1967; Blake & Corcoran, 1972; Eysenck & Folkard, 1980). Thus, introverts may be more aroused than extraverts in the morning whereas extraverts may be more aroused than introverts in the evening (Revelle, Anderson & Humphreys, 1987). In a recent study, Wilson (1990) tried to investigate the relationships between personality, time of day and arousal as measured by skin conductance. The author found that age acts as a possible mediator of relationships between extraversion and skin conductance. The author reported that after making age corrections to the skin conductance curves for extraverts and introverts, the introverts appeared to be higher in skin conductance throughout most of the day. These findings provide clear support for Eysenck’s arousal theory of introversion. Relating personality differences and time of day effects to performance on a vigilance task, Colquhoun (1960) reports that introverts perform better than extraverts in the morning whereas extraverts perform better than introverts in the evening. Blake (1971), Horne et al. (1980), Revelle, Humphreys, Simon and Gilliland (1980), and Knorring, Mornstad, Forsgren and Holmgren (1986) lend support to these findings. However, Westhoff and Kruli (1978) report that time of day and extraversion-introversion as well as their interaction do not produce any significant effect on performance. McLaughlin and Eysenck (1967) postulate that subjects high on neuroticism are more aroused than those low on neuroticism. According to Eysenck (1967b) subjects varying on both extraversion and neuroticism dimensions can be classified into four groups in terms of their arousal levels from low to high, namely stable extraverts (N - E+), stable introverts (N - E-), neurotic extraverts (N + E +) and neurotic introverts (N + E -) (a procedure called ‘Zone Analysis’). Thus, the group with the highest level of arousal is that of neurotic introverts and that of lowest level of arousal consists of individuals who are stable extraverts (Gale, Coles, Kline & Penfold, 1971). The purpose of the present study was to investigate the time of day effects on intelligence test performance in subjects varying on the extraversion and neuroticism dimensions of personality. It PAID
,2/l,-”
1227
1228
SUNITAGUPTA
was predicted that the neurotic introverted group would perform better in the morning while the stable extraverted group would perform better in the evening. METHOD
Subjects
The subjects were selected after a preliminary testing with the Hindi version (Gupta & Poddar, 1979) of the Eysenck Personality Inventory-EPI (Eysenck & Eysenck, 1964). The EPI was initially administered to 2000 female volunteer students of various colleges in a group situation with no group exceeding twenty subjects. The students ranged in age from 16 to 20 years. The students having lie scores of 5 or more were eliminated. The number of such students was 850. The mean and standard deviation for the extraversion scores for the remaining students (n = 1150) were 10.05 and 3.4 and for neuroticism scores 12.02 and 3.59, respectively. ‘On the basis of their scores on the extraversion and neuroticism scales, the subjects were classified into four personality groups namely N - E-t- , N - E - , N + E + and N + E - . The criterion for determining high and low scorers on both extraversion (E) and neuroticism (N) scales was mean f 0.7 SD. The score ranges of the four groups are shown in Table 1. Stimulus material
The stimulus material consisted of Cattell’s (1966) Culture Fair Intelligence Test (CFIT), Scale III, Form A. It consists of 50 items with four subtests, i.e. Series, Classification, Matrices and Topology. Each subtest is separately timed. Design
As there were four levels of personality (N - E + , N - E - , N + E + , and N + E -) and day timings varying at three levels (0900 hours, 1400 hours and 1900 hours), a 4 x 3 factorial design with repeated measures on the second factor was used. Procedure
All the subjects were naive to the experimental problem. Each subject was seated comfortably in the laboratory and a good rapport was established. All the subjects were tested under each of the three timings. There was a gap of 5 days in between two testings. The subjects in each of the four personality groups were counterbalanced by arranging the timings in such a way that an equal number of subjects was subjected to testing as lst, 2nd and 3rd under each of the three timings. All 60 subjects were thus tested with the intelligence scale as per the procedure laid down in the manual at all time conditions. RESULTS
The scores obtained were analysed separately for each of the four subtests as well as for the composite score derived by adding the subtest scores. The results of this study were summarized in Table 2, in which the means and standard deviations of all the subtest and composite scores of CFIT for various personality groups at each time of day are reported. The data were then tested for the assumption of homogeneity of variance. The Cochran test revealed that the assumption was valid. The data were analysed by analysis of variance and the results are reported in Tables 3-7. Table 1. Scores on neuroticism and extraversion scales Personality Group
Each
Score-Range 10 or less on N, 12 or above on E IO or less on N, 7 or less on E 14 or above on N, 12 or above on E 14 or above on N, 7 or less on E
N-E-t N-ENfE+ N+E-
groupconsisted
of 15 subjects.
Time of day and intelligence test performance Table 2. Means and standard Personality group N-E+
Day timing in hours 0900 1400 1900
N-E-
09OJl 1400 1900
N+E+
0900 1400 1900
N+E-
deviation
0900 1400 1900
M SD M SD M SD M SD M SD M SD M SD M SD M SD M SD M SD M SD
Table 3. Results
for personality
x day-timings
groups (n = IS)
CFIT
subtests
Ser
Class
Mat
Top
5.73 1.22 6.00 1.41 6.93 1.53 6.13 1.81 6.00 2.07 6.47 1.92 4.33 2.09 4.27 1.71 5.13 2.37 5.53 2.07 5.53 1.77 6.87 1.81
3.93
7.47 1.30 4.13 2.19 4.33 1.59 4.33 1.49 5.33 1.92 5.53 1.51 3.33
4.27 1.33 4.33 1.63 5.07 1.44 4.07 1.44 4.00 2.04 5.00 1.73 3.47 1.89 4.20 1.52 4.60 1.35 4.00 1.77 3.80 I .89 3.27 1.63
1.58
3.47 1.36 4.87 0.99 3.80 1.15 3.47 1.25 5.00 1.13 3.60 1.72 3.33 1.72 4.67 1.68 4.07 2.12 3.73 I .98 4.93 1.87
of analysis
1.63 3.93 1.34 4.20 1.57 3.60 2.26 3.60 2.09 4.27 2.37
of variance:
1229
Composite 17.40 3.14 17.93 3.92 21.20 3.55 18.33 4.15 18.80 5.58 22.00 4.59 14.73 5.65 15.73 4.23 19.20 5.67 17.20 6.86 16.66 6.08 19.33 6.54
series subtest MS
F
P
Between subjects Personality (P) Subjects within groups
516.06 63.66 452.40
59 3 56
21.22 8.08
2.63
“.S.
Within subjects Day timing (T) PxT T x Subjects within groups
169.33 44.81 7.19 117.33
120 2 6 112
22.40 1.19 1.05
22.02 1.14
0.001 n.s.
source
Subjects
Table 4. Results of analysis
source
df
of variance:
Subiects 294.73 3.26 291.47
59 3 56
Within subjects Day timing (T) PxT T x Subjects within groups
191.33 60.48 0.72 130.13
120 2 6 112
Table 5. Results
of analysis
of variance:
Subjects
df
subtest F
P
1.09 5.21
0.21
n.s.
30.24 0.12 1.16
26.02 0.104
0.001 n.s.
MS
Between subjects Personality (P) Subjects within groups
source
classification
df
matrices
subtest
MS
F
P
Between subjects Personality (P) Subjects within groups
449.66 48.73 400.93
59 3 56
16.24 7.16
2.27
n.s.
Within subjects Day timing Q PxT T x Subiects within arows
178.00 24.84 4.09 149.07
120 2 6 112
12.42 0.68 1.33
9.34 0.51
0.001 n.s.
of variance:
topology
subtest
Table 6. Results of analysis source
Subjects
df
MS
F
P
Between subjects Personality (P) Subjects within groups
286.99 18.95 268.04
59 3 56
6.32 4.79
1.32
n.s.
Within subjects Day timing (T) PxT T x Sub&s within
220.67 9.24 20.27 191.16
120 2 6 112
4.62 3.38 1.71
2.71 1.98
n.s. n.s.
arouos
SLJNITA GUPTA
1230 Table 7. Results
of analvsis
of variance:
comuosite
subtest
Source
Subiects
df
MS
F
Between subjects Personality (P) Subjects within groups
4113.98 252.91 3861.07
59 3 56
84.30 68.95
1.22
Within subjects Day timing (T) PxT T x Subjects within groups
1036.00 448.48 22.59 564.93
120 2 6 112
224.24 3.77 5.04
44.49 0.75
P n.s
0.00 I n.s.
Series subtest
The results given in Table 3 revealed that the main effect of time of day was statistically significant (P < 0.001). The variance attributable to this main effect was evaluated further by the Least Significant Difference (LSD) test. The results indicated that the performance at 1900 hours was better than that at 0900 hours and 1400 hours (P < 0.01 in each case). Classification subtest
The results of ANOVA, given in Table 4, showed that only the main effect of time of day was statistically significant (P < 0.001). The variance attributed to this main effect when evaluated by the LSD test revealed that the performance at 1900 hours was superior to that at 0900 and 1400 hours (P < 0.05 in each case). Matrices subtest
The results, reported in Table 5, indicated that the main effect of time of day was highly significant (P < 0.001). The variance attributed to this main effect when evaluated by the LSD test revealed that the performance at 1900 hours and 1400 hours was superior to that at 0900 hours (P < 0.01 in each case). Topology subtest
The results, reported in Table 6, revealed that neither the main effects of time of day and personality nor their interaction were statistically significant. Composite score
The results reported in Table 7 showed that the main effect of time of day was statistically significant (P < 0.001). The LSD test applied to this main effect indicated that the performance at 1900 hours was better than that at 0900 hours and 1400 hours (P < 0.01 in each case). DISCUSSION
The results, by revealing a statistically significant time of day variable for performance on CFIT clearly, suggest that the performance was the greatest at 1900 hours than at 0900 or 1400 hours. The results are, therefore, highly consistent with the findings of Blake (1967, 1971) who asked naval ratings to perform a number of tasks at 0800, 1030, 1300, 1530 and 2100 hours of day and found that the best level of performance was achieved at 2100 hours. The results thus clearly suggest that there occurs a fairly consistent improvement in performance over the day. This increase in performance can be explained in terms of Yerkes-Dodson Law (1908) i.e. the performance efficiency increases with increase in arousal. According to the Eysenckian theory, the arousal level increases with time of day. Taking body temperature as a measure of arousal, Blake reports that the temperature reaches a peak between 2000 and 2100 hours and a nadir between 0400 and 0500 hours. He also suggests that both the body temperature and performance increase during the course of day. Easterbrook (1959) also reports that high arousal leads to improved performance. The increase in arousal perhaps leads to reduction in the range of cues and proportion of irrelevant cues and thus leads to improvement in performance. The results also reveal that the time of day variable does not interact with personality in its effects on performance. The findings are thus consistent with some of the recent findings (Kerkhof, 1985;
Time of day and intelligence
test performance
1231
Wilson, 1990) but inconsistent with the earlier findings (Colquhoun, 1960; Blake, 1967; Horne & Ostberg, 1977). The results, therefore, clearly demonstrate the effects of time of day on the intelligence test scores. However, the results in respect of topology subtest do not provide support for the earlier findings which suggest that performance efficiency increases with time of day. REFERENCES Blake, M. J. F. (1967). Relationship between circadian rhythm of body temperature and introversion-extraversion. Nature, 215, 896897. Blake, M. J. F. (1971). Temperament and time of day. In Colquhoun, W. P. (Ed.), Biological rhythms and human behaviour. London: Academic Press. Blake, M. J. F. & Corcoran, D. W. J. (1972). Introversion-extraversion and circadian rhythms. Aspects of Human Eficiency, 5, 261-272. Cattell, R. B. (1966). The ZPAT Culture Fair Intelligence Scales 1, 2 and 3 (3rd edn.). Champaign, Ill.: IPAT. Colquhoun, W. P. (1960). Temperament, inspection efficiency and time of day. Ergonomics, 3, 377-378. Easterbrook, J. A. (1959). The effect of emotion on cue utilization on the organization of behaviour. Psychological Review, 66, 183-201. Eysenck, H. J. (1967a). The Biological Basis of Personality. New York: Thomas. Eysenck, H. J. (1967b). Intelligence assessment: A theoretical and experimental approach. British Journal of Educational Psychology, 37, 81-98. Eysenck, H. J. & Eysenck, S. B. G. (1964). Manual of the Eysenck Personality Inventory. London: University of London Press. Eysenck, M. W. & Folkard, S. (1980). Personality, time of day and Caffeine: Some theoretical and conceptual problems in Revelle et al. Journal of Experimental Psychology (General), 109, 3241. Gale, A., Coles, M., Kline, P. & Penfold, V. (1971). Extraversion-introversion, neuroticism and EEG: Basal and response measures during habituation of the orienting response. British Journal of Psychology, 62, 5333.543. Gupta, B. S. & Poddar, M. (1979). Personality traits among Hindi knowing Indian students. Journal of Social Psychology, 107, 279-280. Home, J. A. & Ostberg, 0. (1976). A self-assessment questionnaire to determine morningness-eveningness in human circadian rhythms. International Journal of Chronobiology, 4, 97-110. Horne, J. A. & Ostberg, 0. (1977). Individual differences in human circadian rhythms. Biological Psychology, 5, 179-190. Horne, J. A., Brass, C. G. & Pettitt, A. N. (1980). Circadian performance differences between morning and evening types. Ergonomics, 23, 29936. Kerkhof, G. A. (1985). Inter-individual differences in the human circadian system: A review. Biological psychology, 20, 83-112. Knorring, L. V., Mornstad, H., Forsgren, L. & Holmgren, S. (1986). Saliva secretion rate and saliva concentration in relation to extraversion. Personalily and Individual DifSerences, I, 33-38. McLaughlin, R. J. & Evsenck, H. J. (1967). Extraversion, neuroticism and paired-associate learning. Journalof Experimental Research in Personality, 2, 128-132. Revelle. W.. Anderson. K. J. & Humnhrevs. M. S. (1987). Empirical tests and theoretical extensions of arousal-based theories of personality. In Strelau, J. & Eysenck, H. J. (Eds), Personality dimensions and arousal, pp. 17-36. New York: Plenum Press. Revelle, W., Humphreys, M. S., Simon, L. & Gilliland, K. (1980). The interactive effect of personality, time of day and caffeine: a test of the arousal model. Journal of Experimental Psychology (General), 109, l-31. Westhoff, K. & Kruli, W. R. (1978). Time of day, extraversion and performance on d, test. Zeirschrifr fur Experimentelle and Angew andte Psychologie, 25, 321-326. Wilson, G. D. (1990). Personality, time of day and arousal. Personality and Individual Differences, II, 153-168. Yerkes, R. M. & Dodson, J. D. (1908). The relation of strength of stimulus to rapidity of habit formation. Journal of Comparative and Neurological Psychology, 18, 459482.
11.pp. 1227-1231,
0191~8869/91$3.00+ 0.00 Copyright 0 1991Pergamon Press plc
1991
Printed in Great Britain. All rights reserved
EFFECTS OF TIME OF DAY AND PERSONALITY ON INTELLIGENCE TEST SCORES SUNITA GUPTA Department of Psychology, Guru Nanak Dev University, Amritsar-143005, India (Received
I6 November
I990; accepted for publication
27 March IWI)
Summary-The present investigation was designed to study the time of day effects on intelligence test performance in subjects varying on extraversion and neuroticism dimensions of personality according to a procedure known as ‘zone analysis’. A factorial design involving four levels of personality and three day timings with repeated measures on the second factor was replicated 15 times. Cattell’s Culture Fair Intelligence Test (CFIT), Scale III, Form A served as the criterion measure. The study supports the following conclusions: (1) the performance on the CFIT was better in the evening (1900 hours) than in the morning(0900 hours) and afternoon (1400 hours) except for topology subtest; (2) personality did not produce any effect on CFIT performance; (3) personality and time of day did not interact in their effects on CFIT performance.
INTRODUCTION
Attributing individual differences in personality to the presence of differences in the levels of activity in the cortico reticular loop, Eysenck (1967a) postulates that introverts have a chronically higher level of cortical arousal than extraverts. But human circadian rhythms also play an important role in individual differences. Blake (1967) reports that introverts are more aroused than extraverts only at certain times of the day. Thus people who prefer to work in the morning may be called ‘morning types’ and those who prefer to work in the evening may be called ‘evening types’. Horne and Ostberg (1976) and Horne, Brass and Pettitt (1980) report that morning types show a rapid rise in body temperature during the morning and reach their peak body temperature earlier than evening types. Introverts tend to be ‘morning types’ with higher body temperature in the morning than extraverts, the ‘evening types’ (Blake, 1967; Blake & Corcoran, 1972; Eysenck & Folkard, 1980). Thus, introverts may be more aroused than extraverts in the morning whereas extraverts may be more aroused than introverts in the evening (Revelle, Anderson & Humphreys, 1987). In a recent study, Wilson (1990) tried to investigate the relationships between personality, time of day and arousal as measured by skin conductance. The author found that age acts as a possible mediator of relationships between extraversion and skin conductance. The author reported that after making age corrections to the skin conductance curves for extraverts and introverts, the introverts appeared to be higher in skin conductance throughout most of the day. These findings provide clear support for Eysenck’s arousal theory of introversion. Relating personality differences and time of day effects to performance on a vigilance task, Colquhoun (1960) reports that introverts perform better than extraverts in the morning whereas extraverts perform better than introverts in the evening. Blake (1971), Horne et al. (1980), Revelle, Humphreys, Simon and Gilliland (1980), and Knorring, Mornstad, Forsgren and Holmgren (1986) lend support to these findings. However, Westhoff and Kruli (1978) report that time of day and extraversion-introversion as well as their interaction do not produce any significant effect on performance. McLaughlin and Eysenck (1967) postulate that subjects high on neuroticism are more aroused than those low on neuroticism. According to Eysenck (1967b) subjects varying on both extraversion and neuroticism dimensions can be classified into four groups in terms of their arousal levels from low to high, namely stable extraverts (N - E+), stable introverts (N - E-), neurotic extraverts (N + E +) and neurotic introverts (N + E -) (a procedure called ‘Zone Analysis’). Thus, the group with the highest level of arousal is that of neurotic introverts and that of lowest level of arousal consists of individuals who are stable extraverts (Gale, Coles, Kline & Penfold, 1971). The purpose of the present study was to investigate the time of day effects on intelligence test performance in subjects varying on the extraversion and neuroticism dimensions of personality. It PAID
,2/l,-”
1227
1228
SUNITAGUPTA
was predicted that the neurotic introverted group would perform better in the morning while the stable extraverted group would perform better in the evening. METHOD
Subjects
The subjects were selected after a preliminary testing with the Hindi version (Gupta & Poddar, 1979) of the Eysenck Personality Inventory-EPI (Eysenck & Eysenck, 1964). The EPI was initially administered to 2000 female volunteer students of various colleges in a group situation with no group exceeding twenty subjects. The students ranged in age from 16 to 20 years. The students having lie scores of 5 or more were eliminated. The number of such students was 850. The mean and standard deviation for the extraversion scores for the remaining students (n = 1150) were 10.05 and 3.4 and for neuroticism scores 12.02 and 3.59, respectively. ‘On the basis of their scores on the extraversion and neuroticism scales, the subjects were classified into four personality groups namely N - E-t- , N - E - , N + E + and N + E - . The criterion for determining high and low scorers on both extraversion (E) and neuroticism (N) scales was mean f 0.7 SD. The score ranges of the four groups are shown in Table 1. Stimulus material
The stimulus material consisted of Cattell’s (1966) Culture Fair Intelligence Test (CFIT), Scale III, Form A. It consists of 50 items with four subtests, i.e. Series, Classification, Matrices and Topology. Each subtest is separately timed. Design
As there were four levels of personality (N - E + , N - E - , N + E + , and N + E -) and day timings varying at three levels (0900 hours, 1400 hours and 1900 hours), a 4 x 3 factorial design with repeated measures on the second factor was used. Procedure
All the subjects were naive to the experimental problem. Each subject was seated comfortably in the laboratory and a good rapport was established. All the subjects were tested under each of the three timings. There was a gap of 5 days in between two testings. The subjects in each of the four personality groups were counterbalanced by arranging the timings in such a way that an equal number of subjects was subjected to testing as lst, 2nd and 3rd under each of the three timings. All 60 subjects were thus tested with the intelligence scale as per the procedure laid down in the manual at all time conditions. RESULTS
The scores obtained were analysed separately for each of the four subtests as well as for the composite score derived by adding the subtest scores. The results of this study were summarized in Table 2, in which the means and standard deviations of all the subtest and composite scores of CFIT for various personality groups at each time of day are reported. The data were then tested for the assumption of homogeneity of variance. The Cochran test revealed that the assumption was valid. The data were analysed by analysis of variance and the results are reported in Tables 3-7. Table 1. Scores on neuroticism and extraversion scales Personality Group
Each
Score-Range 10 or less on N, 12 or above on E IO or less on N, 7 or less on E 14 or above on N, 12 or above on E 14 or above on N, 7 or less on E
N-E-t N-ENfE+ N+E-
groupconsisted
of 15 subjects.
Time of day and intelligence test performance Table 2. Means and standard Personality group N-E+
Day timing in hours 0900 1400 1900
N-E-
09OJl 1400 1900
N+E+
0900 1400 1900
N+E-
deviation
0900 1400 1900
M SD M SD M SD M SD M SD M SD M SD M SD M SD M SD M SD M SD
Table 3. Results
for personality
x day-timings
groups (n = IS)
CFIT
subtests
Ser
Class
Mat
Top
5.73 1.22 6.00 1.41 6.93 1.53 6.13 1.81 6.00 2.07 6.47 1.92 4.33 2.09 4.27 1.71 5.13 2.37 5.53 2.07 5.53 1.77 6.87 1.81
3.93
7.47 1.30 4.13 2.19 4.33 1.59 4.33 1.49 5.33 1.92 5.53 1.51 3.33
4.27 1.33 4.33 1.63 5.07 1.44 4.07 1.44 4.00 2.04 5.00 1.73 3.47 1.89 4.20 1.52 4.60 1.35 4.00 1.77 3.80 I .89 3.27 1.63
1.58
3.47 1.36 4.87 0.99 3.80 1.15 3.47 1.25 5.00 1.13 3.60 1.72 3.33 1.72 4.67 1.68 4.07 2.12 3.73 I .98 4.93 1.87
of analysis
1.63 3.93 1.34 4.20 1.57 3.60 2.26 3.60 2.09 4.27 2.37
of variance:
1229
Composite 17.40 3.14 17.93 3.92 21.20 3.55 18.33 4.15 18.80 5.58 22.00 4.59 14.73 5.65 15.73 4.23 19.20 5.67 17.20 6.86 16.66 6.08 19.33 6.54
series subtest MS
F
P
Between subjects Personality (P) Subjects within groups
516.06 63.66 452.40
59 3 56
21.22 8.08
2.63
“.S.
Within subjects Day timing (T) PxT T x Subjects within groups
169.33 44.81 7.19 117.33
120 2 6 112
22.40 1.19 1.05
22.02 1.14
0.001 n.s.
source
Subjects
Table 4. Results of analysis
source
df
of variance:
Subiects 294.73 3.26 291.47
59 3 56
Within subjects Day timing (T) PxT T x Subjects within groups
191.33 60.48 0.72 130.13
120 2 6 112
Table 5. Results
of analysis
of variance:
Subjects
df
subtest F
P
1.09 5.21
0.21
n.s.
30.24 0.12 1.16
26.02 0.104
0.001 n.s.
MS
Between subjects Personality (P) Subjects within groups
source
classification
df
matrices
subtest
MS
F
P
Between subjects Personality (P) Subjects within groups
449.66 48.73 400.93
59 3 56
16.24 7.16
2.27
n.s.
Within subjects Day timing Q PxT T x Subiects within arows
178.00 24.84 4.09 149.07
120 2 6 112
12.42 0.68 1.33
9.34 0.51
0.001 n.s.
of variance:
topology
subtest
Table 6. Results of analysis source
Subjects
df
MS
F
P
Between subjects Personality (P) Subjects within groups
286.99 18.95 268.04
59 3 56
6.32 4.79
1.32
n.s.
Within subjects Day timing (T) PxT T x Sub&s within
220.67 9.24 20.27 191.16
120 2 6 112
4.62 3.38 1.71
2.71 1.98
n.s. n.s.
arouos
SLJNITA GUPTA
1230 Table 7. Results
of analvsis
of variance:
comuosite
subtest
Source
Subiects
df
MS
F
Between subjects Personality (P) Subjects within groups
4113.98 252.91 3861.07
59 3 56
84.30 68.95
1.22
Within subjects Day timing (T) PxT T x Subjects within groups
1036.00 448.48 22.59 564.93
120 2 6 112
224.24 3.77 5.04
44.49 0.75
P n.s
0.00 I n.s.
Series subtest
The results given in Table 3 revealed that the main effect of time of day was statistically significant (P < 0.001). The variance attributable to this main effect was evaluated further by the Least Significant Difference (LSD) test. The results indicated that the performance at 1900 hours was better than that at 0900 hours and 1400 hours (P < 0.01 in each case). Classification subtest
The results of ANOVA, given in Table 4, showed that only the main effect of time of day was statistically significant (P < 0.001). The variance attributed to this main effect when evaluated by the LSD test revealed that the performance at 1900 hours was superior to that at 0900 and 1400 hours (P < 0.05 in each case). Matrices subtest
The results, reported in Table 5, indicated that the main effect of time of day was highly significant (P < 0.001). The variance attributed to this main effect when evaluated by the LSD test revealed that the performance at 1900 hours and 1400 hours was superior to that at 0900 hours (P < 0.01 in each case). Topology subtest
The results, reported in Table 6, revealed that neither the main effects of time of day and personality nor their interaction were statistically significant. Composite score
The results reported in Table 7 showed that the main effect of time of day was statistically significant (P < 0.001). The LSD test applied to this main effect indicated that the performance at 1900 hours was better than that at 0900 hours and 1400 hours (P < 0.01 in each case). DISCUSSION
The results, by revealing a statistically significant time of day variable for performance on CFIT clearly, suggest that the performance was the greatest at 1900 hours than at 0900 or 1400 hours. The results are, therefore, highly consistent with the findings of Blake (1967, 1971) who asked naval ratings to perform a number of tasks at 0800, 1030, 1300, 1530 and 2100 hours of day and found that the best level of performance was achieved at 2100 hours. The results thus clearly suggest that there occurs a fairly consistent improvement in performance over the day. This increase in performance can be explained in terms of Yerkes-Dodson Law (1908) i.e. the performance efficiency increases with increase in arousal. According to the Eysenckian theory, the arousal level increases with time of day. Taking body temperature as a measure of arousal, Blake reports that the temperature reaches a peak between 2000 and 2100 hours and a nadir between 0400 and 0500 hours. He also suggests that both the body temperature and performance increase during the course of day. Easterbrook (1959) also reports that high arousal leads to improved performance. The increase in arousal perhaps leads to reduction in the range of cues and proportion of irrelevant cues and thus leads to improvement in performance. The results also reveal that the time of day variable does not interact with personality in its effects on performance. The findings are thus consistent with some of the recent findings (Kerkhof, 1985;
Time of day and intelligence
test performance
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Wilson, 1990) but inconsistent with the earlier findings (Colquhoun, 1960; Blake, 1967; Horne & Ostberg, 1977). The results, therefore, clearly demonstrate the effects of time of day on the intelligence test scores. However, the results in respect of topology subtest do not provide support for the earlier findings which suggest that performance efficiency increases with time of day. REFERENCES Blake, M. J. F. (1967). Relationship between circadian rhythm of body temperature and introversion-extraversion. Nature, 215, 896897. Blake, M. J. F. (1971). Temperament and time of day. In Colquhoun, W. P. (Ed.), Biological rhythms and human behaviour. London: Academic Press. Blake, M. J. F. & Corcoran, D. W. J. (1972). Introversion-extraversion and circadian rhythms. Aspects of Human Eficiency, 5, 261-272. Cattell, R. B. (1966). The ZPAT Culture Fair Intelligence Scales 1, 2 and 3 (3rd edn.). Champaign, Ill.: IPAT. Colquhoun, W. P. (1960). Temperament, inspection efficiency and time of day. Ergonomics, 3, 377-378. Easterbrook, J. A. (1959). The effect of emotion on cue utilization on the organization of behaviour. Psychological Review, 66, 183-201. Eysenck, H. J. (1967a). The Biological Basis of Personality. New York: Thomas. Eysenck, H. J. (1967b). Intelligence assessment: A theoretical and experimental approach. British Journal of Educational Psychology, 37, 81-98. Eysenck, H. J. & Eysenck, S. B. G. (1964). Manual of the Eysenck Personality Inventory. London: University of London Press. Eysenck, M. W. & Folkard, S. (1980). Personality, time of day and Caffeine: Some theoretical and conceptual problems in Revelle et al. Journal of Experimental Psychology (General), 109, 3241. Gale, A., Coles, M., Kline, P. & Penfold, V. (1971). Extraversion-introversion, neuroticism and EEG: Basal and response measures during habituation of the orienting response. British Journal of Psychology, 62, 5333.543. Gupta, B. S. & Poddar, M. (1979). Personality traits among Hindi knowing Indian students. Journal of Social Psychology, 107, 279-280. Home, J. A. & Ostberg, 0. (1976). A self-assessment questionnaire to determine morningness-eveningness in human circadian rhythms. International Journal of Chronobiology, 4, 97-110. Horne, J. A. & Ostberg, 0. (1977). Individual differences in human circadian rhythms. Biological Psychology, 5, 179-190. Horne, J. A., Brass, C. G. & Pettitt, A. N. (1980). Circadian performance differences between morning and evening types. Ergonomics, 23, 29936. Kerkhof, G. A. (1985). Inter-individual differences in the human circadian system: A review. Biological psychology, 20, 83-112. Knorring, L. V., Mornstad, H., Forsgren, L. & Holmgren, S. (1986). Saliva secretion rate and saliva concentration in relation to extraversion. Personalily and Individual DifSerences, I, 33-38. McLaughlin, R. J. & Evsenck, H. J. (1967). Extraversion, neuroticism and paired-associate learning. Journalof Experimental Research in Personality, 2, 128-132. Revelle. W.. Anderson. K. J. & Humnhrevs. M. S. (1987). Empirical tests and theoretical extensions of arousal-based theories of personality. In Strelau, J. & Eysenck, H. J. (Eds), Personality dimensions and arousal, pp. 17-36. New York: Plenum Press. Revelle, W., Humphreys, M. S., Simon, L. & Gilliland, K. (1980). The interactive effect of personality, time of day and caffeine: a test of the arousal model. Journal of Experimental Psychology (General), 109, l-31. Westhoff, K. & Kruli, W. R. (1978). Time of day, extraversion and performance on d, test. Zeirschrifr fur Experimentelle and Angew andte Psychologie, 25, 321-326. Wilson, G. D. (1990). Personality, time of day and arousal. Personality and Individual Differences, II, 153-168. Yerkes, R. M. & Dodson, J. D. (1908). The relation of strength of stimulus to rapidity of habit formation. Journal of Comparative and Neurological Psychology, 18, 459482.