Development of sleep during monotonous stimulation as related to individual differences

This study was designed to examine whether the sleep-promoting effect of monotonous stimulation depends on individual differences in strength of the nervous system, as was suggested by Pavlov. Sixty male subjects were divided into three groups, depending on their score on the “strength of excitation” scale of the Strelau Temperament Inventory. Within each group, subjects were randomly assigned to be exposed to either a) a sequence of tones or b) “no tones” (i.e., a quiet room). Dependent variables were latencies to Sleep Stage 1 (SOL 1) and Sleep Stage 2 (SOL 2). The main effects of stimulation and strength of the nervous system were not statistically significant. However, there was a significant interaction between stimulation and strength for both dependent variables. “Weak” subjects tended to fall asleep more rapidly during monotonous stimulation, whereas the reverse was true of “strong” subjects. The results suggest that individual differences might play an important role in the development of sleep during monotonous stimulation.     

Statistical evaluation of measures of fit in the Lingoes-Borg procrustean individual differences scaling

PINDIS, as recently presented by Lingoes and Borg [1978] not only marks the latest development within the scope of individual differences scaling, but, may be of benefit in some closely related topics, such as target analysis. Decisions on whether the various models available from PINDIS fit fallible data are relatively arbitrary, however, since a statistical theory of the fit measures is lacking. Using Monte Carlo simulation, expected fit measures as well as some related statistics were therefore obtained by scaling sets of 4(4)24 random configurations of 5(5)30 objects in 2, 3, and 4 dimensions (individual differences case) and by fitting one random configuration to a fixed random target for 5(5)30 objects in 2, 3, and 4 dimensions (target analysis case). Applications are presented.     

Balanced incomplete blocks to control individual differences

Balanced incomplete block designs are used when there are reasons that preclude the use of repeated measurements designs, particularly when there are at least two factors, each with several levels. However, these designs are usually not used when interaction effects are of interest, because they involve the confounding of the interactions with subject or group differences. This paper describes special computational procedures that can be employed to obtain partial, but unconfounded, information about interaction effects.     

Reconnecting interpretation to reasoning through individual differences

Computational theories of mind assume that participants interpret information and then reason from those interpretations. Research on interpretation in deductive reasoning has claimed to show that subjects' interpretation of single syllogistic premises in an “immediate inference” task is radically different from their interpretation of pairs of the same premises in syllogistic reasoning tasks (Newstead, 1989, 1995; Roberts, Newstead, & Griggs, 2001). Narrow appeal to particular Gricean implicatures in this work fails to bridge the gap. Grice's theory taken as a broad framework for credulous discourse processing in which participants construct speakers' “intended models” of discourses can reconcile these results, purchasing continuity of interpretation through variety of logical treatments. We present exploratory experimental data on immediate inference and subsequent syllogistic reasoning. Systematic patterns of interpretation driven by two factors (whether the subject's model of the discourse is credulous, and their degree of reliance on information packaging) are shown to transcend particular quantifier inferences and to drive systematic differences in subjects' subsequent syllogistic reasoning. We conclude that most participants do not understand deductive tasks as experimenters intend, and just as there is no single logical model of reasoning, so there is no reason to expect a single “fundamental human reasoning mechanism”.     

Reconnecting interpretation to reasoning through individual differences

Computational theories of mind assume that participants interpret information and then reason from those interpretations. Research on interpretation in deductive reasoning has claimed to show that subjects' interpretation of single syllogistic premises in an “immediate inference” task is radically different from their interpretation of pairs of the same premises in syllogistic reasoning tasks (Newstead, 1989, 1995; Roberts, Newstead, & Griggs, 2001). Narrow appeal to particular Gricean implicatures in this work fails to bridge the gap. Grice's theory taken as a broad framework for credulous discourse processing in which participants construct speakers' “intended models” of discourses can reconcile these results, purchasing continuity of interpretation through variety of logical treatments. We present exploratory experimental data on immediate inference and subsequent syllogistic reasoning. Systematic patterns of interpretation driven by two factors (whether the subject's model of the discourse is credulous, and their degree of reliance on information packaging) are shown to transcend particular quantifier inferences and to drive systematic differences in subjects' subsequent syllogistic reasoning. We conclude that most participants do not understand deductive tasks as experimenters intend, and just as there is no single logical model of reasoning, so there is no reason to expect a single “fundamental human reasoning mechanism”.     

Memory span as a measure of individual differences in memory capacity

Two experiments were carried out to investigate whether the immediate digit span measure traditionally used in the assessment of individual differences in cognition is a good predictor of performance on other memory tasks. In the first experiment, it was found that subjects’ digit spans were not significantly related to their performances on either short-term or longterm memory tasks, or to theoretical measures of their memory store capacities. Memory for the temporal occurrence of events, however, proved to be positively correlated with digit span. A second experiment confirmed that digit span was correlated with memory for the temporal occurrence of events, but not with item memory. Thus it was concluded that an individual’s digit span reflects his ability to retain information about the order of a sequence of events rather than the capacity of his short- or long-term memory.     

Trait empathy as a predictor of individual differences in perceived loneliness

Loneliness has been shown to be inversely correlated with empathy in younger adults. The present study extends previous research by investigating the association between empathy and loneliness across the adult lifespan and examining the role of relevant demographic and personality factors. 110 community-dwelling adults (18 to 81 years old) completed the UCLA Loneliness Scale and the Empathy Quotient. Empathy scores were inversely associated with rated loneliness and predicted 8.7% of variance in loneliness scores after accounting for sex, age, relationship status, education, and neuroticism. The Social Skills factor of the Empathy Quotient was the strongest predictor of the association between perceived empathy and loneliness. Previous research is extended by the finding that rated loneliness was inversely associated with empathy scores across the adult lifespan. Underlying this relationship may be negative perceptions of personal social proclivity as a function of difficulty in understanding the mental states of others and high trait neuroticism.     

Hormones and personality: Testosterone as a marker of individual differences

Recently, testosterone (T) has been linked to behaviors that are conceptually related to dominance as a personality characteristic. Although evidence for this association is growing, the psychometric properties of T as an individual difference variable have been largely neglected. For T to be considered a biological marker of dispositional dominance it is critical that it demonstrates high test–retest reliability and good convergent and discriminant validity. Two studies tested the temporal stability of salivary T in humans and the relationship between T and traditional measures of personality. Across both studies, test–retest reliability for T was high and comparable to the short-term stability of questionnaire-based and implicitly assessed personality assessment instruments. In being modestly correlated with self-reported dominance, T showed some evidence of convergent validity. In being statistically independent from conceptually unrelated personality constructs (such as Emotional Stability and Openness to Experience) it showed good evidence of discriminant validity. The findings strengthen the psychometric foundation for using T as a hormonal marker of individual differences.     

An individual differences approach to the halo-accuracy paradox

In performance appraisal, the halo-accuracy paradox describes the surprising result that rater accuracy can be positively correlated with the halo rating error. Fisicaro (1988) provided an explanation for this unlikely relationship by proposing an inverse V function as the relationship between accuracy and invalid halo in which maximum accuracy is located at zero invalid halo. This paper develops the model by proposing that maximum accuracy does not have to be at zero invalid (Hypothesis 1). As the cognitive difficulty of a rating task increases, a negative monotonie relationship between maximum achievable accuracy and associated value of absolute invalid halo is specified (Hypothesis 2). The hypotheses were tested in two different experimental situations. Results from both studies supported Hypothesis 1 but, whilst a distinct pattern between accuracy and absolute invalid halo was noted, only a weak version of Hypothesis 2 could be supported. The evidence from this paper demonstrates that the halo-accuracy paradox is not an artefact as some recent reviewers have proposed (Balzer & Sulsky, 1992; Murphy & Balzer, 1989; Murphy & Cleveland, 1991).     

Five potential principles for understanding cultural differences in relation to individual differences

This paper deals with psychological differences between two cultures, with respect to the differences between individuals in those same cultures. Five principles are presented which describe either actual or probable empirical relationships between within- and between-culture differences, and a possible theoretical account is given for each of the presumed differences. (1) The differences between “cultures” seem “bigger” than the actual differences between the individuals in these same cultures. This relation is attributed to the idea that universal human biological predispositions are often opposed by cultural traditions, so the outcome is somewhat of a compromise between the two. (2) Differences between individuals in different cultures are generally larger in behavior than in thoughts or feelings This is attributed to the fact that it is easier to socialize behavior than mental events. (3) Many cultural differences are expressed in individuals in terms of different default responses or interpretations or preferences for the same situation. Dominant responses in one culture are usually a less salient part of the repertoire of individuals in another culture. (4) Much of the effect of culture, and our impression of culture differences, results from the physical/social artifacts (environments, institutions) created by the culture. There is a strong tendency by psychologists to under-rate or ignore the effects of the physical environment. (5) In the contemporary world, differences between individuals in two cultures will be larger in older generations. Cultural differences may be markedly reduced in the most recent generations, on account of globalization. The position put forth is an attempt to integrate the ideas that there are real human predispositions of various sorts and that culture is a powerful force, and to explain why it is surprisingly easy for us to understand the viewpoint of people from other cultures (their “reality”is often a less preferred alternative in our own repertoire).     

Explorations of individual differences relevant to high level skill

Past research has uncovered few broad abilities that underlie high skill. In this paper, attempts to isolate three different abilities of potential relevance to skill are described. No evidence was found for a general time-sharing ability in common to different kinds of tasks. Modest evidence was found for a trait of attentional flexibility. That trait could potentially be of use in predicting success for skills that require rapid shifts of attention because of rapidly changing task demands. Finally, the rate of repetitive activity is correlated across different muscle groups. For example, finger tapping speed is correlated with foot tapping speed, suggesting a common rate limiting factor. In turn, those rates predict handwriting speed and, according to Book (1924), championship typing.     

Scale properties of the Holtzman inkblots

Scaling techniques were presently applied to perceptions of inkblots, to empirically delineate the relationship between their stimulus properties and the nature of verbal associations elicited in projective testing. The Holtzman Inkblot Technique (HIT) was administered in group form to a relatively diverse group of college students. Subjects also individually rated the similarity of pairs of the HIT inkblots. Similarity judgments were analyzed via a multidimensional scaling (MDS) approach which recovered dimensions of variations among blots. The MDS procedures also captured variation across subjects in their utilization of blot stimulus properties. MDS solutions generally reflected differences among the blots along dimensions of physical characteristics of the blots. Differences in responsiveness of subjects to these characteristics appeared to reliably reflect meaningful substantive distinctions among subjects, many of which were not captured by traditional HIT variables. Implications were discussed in terms of further MDS applications and possible re-evaluation of HIT variables or procedures.     

Relationships between Growth need Strength and selected individual differences measures employed in job design research

The present study examines the degree to which the Growth Need Strength scales (Job Choice and Would Like formats) of the Job Diagnostic Survey (Hackman & Oldham, Journal of Applied Psychology, 1975, 60, 159–170) correlate with (a) other measures of needs and values employed in research as moderators of the job scope-job satisfaction relationship and (b) a measure of social desirability. Results showed (a) only moderate correlations between the Growth Need Strength scales and the other measures of needs and values and (b) a relatively high degree of correlation between social desirability and the Would Like measure of Growth Need Strength. Implications of these findings for job design research are considered.