Familial aspects of male homosexuality.

Research has generally supported the existence of familial-genetic factors for male sexual orientation, but has not shed much light on the specific nature of those influences. Gay men with gay brothers provide the opportunity to examine several hypotheses. Sixty-six men, representing 37 gay male sibling pairs, completed questionnaires assessing behavior on various measures including childhood and adult gender nonconformity, timing of awareness of homosexual feelings, self-acceptance, and the quality of family relationships. Consistent with prior findings using twins, gay brothers were similar in their degree of childhood gender non-conformity, suggesting that this variable may distinguish etiologically (e.g., genetically) heterogeneous subtypes. The large majority of gay men with brothers knew about their own homosexual feelings before they learned about their brothers' homosexual feelings, suggesting that discovery of brothers' homosexuality is not an important cause of male homosexuality.

Individual differences in the phase and amplitude of the human circadian temperature rhythm: with an emphasis on morningness-eveningness.

We studied the relationship between the phase and the amplitude of the circadian temperature rhythm using questionnaires that measure individual differences in personality variables, variables that relate to circadian rhythms, age and sex. The ambulatory core body temperature of 101 young men and 71 young women was recorded continuously over 6 days. The temperature minimum (Tmin) and amplitude (Tamp) were derived by fitting a complex cosine curve to each day's data for each subject. Participants completed the Horne-Ostberg Morningness-Eveningness Questionnaire (MEQ), the Circadian Type Inventory (CTI) and the MMPI-2, scored for the Psychopathology-5 (PSY-5) personality variables. We found that the average Tmin occurred at 03.50 h for morning-types (M-types), 05.02 h for the neither-types and 06.01 h for evening-types (E-types). Figures were presented that could provide an estimate of Tmin given an individual's morningness-eveningness score or weekend wake time. The Tmin occurred at approximately the middle of the 8-h sleep period, but it occurred closer to wake in subjects with later Tmin values and increasing eveningness. In other words, E-types slept on an earlier part of their temperature cycle than M-types. This difference in the phase-relationship between temperature and sleep may explain why E-types are more alert at bedtime and sleepier after waking than M-types. The Tmin occurred about a half-hour later for men than women. Another interesting finding included an association between circadian rhythm temperature phase and amplitude, in that subjects with more delayed phases had larger amplitudes. The greater amplitude was due to lower nocturnal temperature.

Impulsivity and time of day: is rate of change in arousal a function of impulsivity?

Impulsivity has been interpreted as a stable mediator of rate of change in arousal states. To test this hypothesis, 129 Ss differing in impulsivity were given placebo or caffeine at 9:00 a.m. or 7:30 p.m. Recognition memory was tested for the last 20 items from 2 lists of 24 items and 2 lists of 80 items. Scores from this paradigm reflect sustained attention and are thus sensitive to changes in arousal. A 4-way interaction among impulsivity, time of day, drug, and prior stimuli (p < .05) indicated that for those given placebo, recognition memory for long and late lists was poorer the higher the impulsivity in the morning; this pattern reversed in the evening. Caffeine reduced recognition errors. These results indicate that impulsivity is not a stable predictor of rate of change in arousal states. Instead, susceptibility to attentional lapses is mediated by impulsivity-related phase differences in diurnal arousal rhythms.

Increased heritability for lower IQ levels?

Detterman et al. (1990) presented evidence based on twins that the heritability of IQ may be higher in the lower part of the IQ range. We first offer an alternative test for differential heritability across the IQ range, based on the analysis of absolute intrapair differences of monozygotic versus dizygotic twins. We then review two previous studies, each containing more twins than the sample of Detterman et al., which examined the distribution of intrapair absolute differences. In contrast to the study of Detterman et al., both yielded results more compatible with higher heritability in the upper range of IQ. We discuss various interpretations of these findings and show how our proposed test might aid in distinguishing among them.

Personality and conditioning: a test of four models.

Four experiments were conducted to test hypotheses derived from 4 alternative models of individual differences in instrumental conditioning. A standard go--no-go discrimination learning task was used in each of the 4 experiments. The results indicate that individual differences in performance of this discrimination are more consistently and strongly associated with impulsivity and anxiety than with extraversion and neuroticism. In each of the experiments, high anxiety hindered the learning of a go--no-go discrimination more among high impulsive Ss than among low impulsive Ss, and in 2 of the experiments high anxiety actually facilitated learning among low impulsive Ss. These findings are incompatible with Eysenck's and Gray's hypotheses regarding extraversion but are not inconsistent with Newman's. Aspects of these results do support Spence's and Gray's models of anxiety and instrumental conditioning. However, both of these models were contradicted by other trends in the data. A modification of Gray's model of impulsivity and anxiety that emphasizes the role of expectancies was proposed to fit these data.

Effects of anxiety on analogical reasoning: a test of three theoretical models.

Three mediational theories of anxiety and performance, namely, cue utilization theory (Easterbrook, 1959), attentional theory (Mandler & Sarason, 1952; Wine, 1971), and working memory capacity theory (M. W. Eysenck, 1979), were compared for their efficacy in explaining anxiety-induced performance decrements on a task of analogical reasoning. One hundred two subjects who varied in their trait and state anxiety levels completed 100 geometric analogies under either relaxed (reassurance, non-time-limited) or stressed (ego-threat, time-limited) conditions. Response time and error rate data for nine levels of task complexity (1-, 2-, and 3-element analogies with zero, one, or two transformations per element) were analyzed by means of multivariate analysis of variance. Results in the relaxed condition supported attentional theory in that the more anxious subjects were both slower and less accurate than were the less anxious subjects. In the stressed condition, none of the three anxiety-performance theories was supported. More anxious subjects were faster but made more errors than did less anxious subjects. Thus in the stressed condition, performance differences suggested differences in speed-accuracy trade-off strategies rather than differences in processing abilities. The limitations of attentional theory and the need to study the effects of anxiety and time stress on information processing are discussed.

Individual differences in the use of simplification strategies in a complex decision-making task.

Decision time results were used to assess the strategies that 90 college undergraduates used in a complex decision-making task. Trend analyses revealed that the functions relating choice time to the number of choice alternatives in a set and the number of attributes comprising those alternatives contained linear (increasing) components. In addition, for a portion of the subjects, there was a quadratic effect of the number of attributes available to the decision maker on choice time, suggesting that these subjects adopted simplification strategies at high levels of task complexity. Reliable individual differences in these trend components were observed, consistent with individual differences in motivation and/or processing capacities. These individual differences were included in an information-processing model of decision behavior that captured the choice time data observed in this study. Subjects' ratings of apartments were used as a basis to assess the extent to which the use of simplification strategies resulted in preference reversals. Contrary to expectation, subjects whose choice times contained quadratic components demonstrated fewer preference reversals at high levels of information load.

Personality traits: fact or fiction? A critique of the Shweder and D'Andrade systematic distortion hypothesis.

According to Shweder and D'Andrade (1979, 1980), covariation in memory-based ratings of people's behavior is determined more by semantic relations between behavior categories than by actual co-occurrence. They claim therefore that the existence of personality traits is largely a fiction supported by our conceptions rather than by reality. Contrary to this hypothesis, we argue that semantics are logically implicated in both the observation and recall of behavior and that support for this assumption can be found if immediate encodings of behavior are as sensitively scaled as subsequent memory-based ratings. Results of a demonstration experiment supported this conclusion. When immediate encodings were scaled across all behavior categories, the relation between semantics and memory was completely explained by the role of semantics in the immediate encoding of behavior. However, when immediately encoded behavior was simply identified (rather than scaled), support for systematic distortion was obtained. Previous support for the systematic distortion hypothesis may therefore be attributed to the use of too simple a coding scheme for the measurement of immediate behavior. Implications for the existence of personality traits and for personality measurement are discussed.

Impulsivity, caffeine, and proofreading: a test of the Easterbrook hypothesis.

Easterbrook's (1959) suggestion that arousal is inversely related to the range of cue utilization has been frequently cited as an explanation for the curvilinear relationship between arousal and performance. There is very little empirical support for this position, however. As a test of the Easterbrook hypothesis, 60 undergraduates who varied in their impulsivity level were given caffeine or placebo and then asked to proofread several passages. Estimates of sensitivity were calculated using signal detection techniques. It was predicted that high arousal would reduce sensitivity to interword errors, which require a broad range of cue utilization, but that the observed levels of arousal would not affect sensitivity to intraword errors, which require a minimal range of cue utilization. A significant crossover interaction between impulsivity and drug for interword errors indicated that caffeine increased the error detection rate of the (less aroused) more impulsive subjects but lowered the error detection rate of the (more aroused) less impulsive subjects. The results of this study support the suggestion that arousal has direct effects on the capacity for simultaneous information processing, independent of its effects on performance speed.

The interactive effect of personality, time of day, and caffeine: a test of the arousal model.

The personality dimension of introversion/extraversion is one of the few personality dimensions that can be reliably identified from study to study and investigator to investigator. The importance of this demension within personality theory is due both to the stability of the trait and the influential theory of H. J. Eysenck. The basic assumption in Eysenck's theory of introversion/extraversion is that the personality differences between introverts and extraverts reflect some basic difference in the resting level of cortical arousal or activation. Assuming that there is a curvilinear relationship (an inverted U) between levels of stress and performance leads to a test of this arousal theory. That is, moderate increases in stress should hinder the performance of introverts who are presumably already highly aroused. However, the same moderate increase in stress might help the performance of the presumably underaroused extraverts. Revelle, Amaral, and Turriff reported that the administration of moderate doses of caffeine hindered the performance of introverts and helped the performance of extraverts on a cognitive task similar to the verbal test of the Graduate Record Examination. Assuming that caffeine increases arousal, this interaction between introversion/extraversion and drug condition supports Eysenck's theory. This interaction was explored in a series of experiments designed to replicate, extend, and test the generality of the original finding. The interaction between personality and drug condition was replicated and extended to additional cognitive performance tasks. However, these interactions were affected by time of day and stage of practice, and the subscales of introversion/extraversion, impulsivity, and sociability, were differentially affected. In the morning of the first day, low impulsives were hindered and high impulsives helped by caffeine. This pattern reversed in the evening of the first day, and it reversed again in the evening of Day 2. We concluded that the results from the first day of testing require a revision of Eysenck's theory. Instead of a stable difference in arousal between low and high impulsives, it appeared that these groups differed in the phase of their diurnal arousal rhythms. The result is that low impulsives are more aroused in the morning and less aroused in the evening than are the high impulsives. A variety of peripheral or strategic explanations (differences in caffeine consumption, guessing strategies, distraction, etc.) for the observed performance increments and decrements were proposed and tentatively rejected. It seems probable that some fundamental change in the efficiency with which information is processes is responsible for these performance changes.

Individual differences in diurnal rhythms and multiple activation states: a reply to M. W. Eysenck and Folkard.

Three issues raised by M. W. Eysenck and Folkard are discussed. These include (a) just what individual difference variable is mediating the time of day and caffeine effects; (b) what the difference is in the diurnal rhythms of low and high impulsives; and (c) whether it is necessary to postulate multiple activation states. Suggestions for future research are then given.

Hierarchical Cluster Analysis And The Internal Structure Of Tests.

Hierachical cluster analysis is shown to be an effective method for forming scales from sets of items. The number of scales to form from a particular item pool is found by testing the psychometric adequacy of each potential scale. Higher-order scales are formed when they are more adequate than their component sub-scales. It is suggested that a scale's adequacy should be assessed by a new measure of internal consistency reliability, coefficient beta, which is defined as the worst split-half reliability of the test. Comparisons with other procedures show that hierarchical clustering algorithms using this psychometrically based decisions rule can be more useful for scale construction using large item pools than are conventional factor analytic techniques.

Very Simple Structure: An Alternative Procedure For Estimating The Optimal Number Of Interpretable Factors.

A new procedure for determining the optimal number of interpretable factors to extract from a correlation matrix is introduced and compared to more conventional procedures. The new method evaluates the magnitude of the Very Simple Structure index of goodness of fit for factor solutions of increasing rank. The number of factors which maximizes the VSS criterion is taken as being the optimal number of factors to extract. Thirty-two artificial and two real data sets are used in order to compare this procedure with such methods as maximum likelihood, the eigenvalue greater than 1.0 rule, and comparison of the observed eigenvalues with those expected from random data.

Introversion/extroversion, time stress, and caffeine: effect on verbal performance.

Time pressure and caffeine differentially affected the performance of introverts on verbal ability tests similar to the Graduate Record Examination. With time pressure and 200 milligrams of caffeine, the performance of introverts fell by 0.63 standard deviation, but extroverts by 0.44 standard deviation.