Exploring temperamental differences in infants from the USA and the Netherlands

This longitudinal study employed the Infant Behaviour Questionnaire-Revised in assessing temperamental differences between infants at 6 months (n = 114 US, 184 Dutch) and 12 months (n = 92 US, 172 Dutch) from the USA and the Netherlands. Main effects indicated that Dutch infants were rated higher on the Orienting/Regulatory Capacity (ORC) factor and fine-grained dimensions of smiling and laughter, falling reactivity, cuddliness, low-intensity pleasure, and soothability, whereas US infants received higher ratings on the Negative Affectivity factor and on dimensions of activity level, vocal reactivity, fear, frustration, and sadness. Cultural differences for ORC were more pronounced in early infancy, cultural differences for Fear were stronger in late infancy, and US infants demonstrated higher duration of orienting at 12 months only. Culture also appeared to impact the pace of consolidation of temperamental characteristics, with greater stability exhibited by US than Dutch infants in smiling and laughter and vocal reactivity.     

Individual differences in personality and face identification

Unfamiliar face identification is characterised by substantial variation between individual observers, but the cause of this variation is largely unknown. This study investigated whether individual differences in face identification are linked to an observer's personality, by combining performance on an established face-matching test with two in-depth personality assessments (the 16PF5 and the NEO-PI-R). The face test revealed a broad distribution in identification ability, but associations between face perception and personality were found only in female observers. In this group, correct face identifications related to low anxiety, low tension, and high emotional stability. These results suggest that associations between personality and face perception are limited, and are confined to anxiety and facets of neuroticism.     

Assessing individual differences in the degree to which people are committed to following their beliefs

The authors developed a new dispositional measure of Commitment to Beliefs (CTB)—the degree to which people feel it is important to follow their value-expressive beliefs—across three phases of research. In Phases 1 and 2 (Studies 1-4), the CTB scale demonstrated strong internal consistency, and convergent and discriminant validity. Phase 3 demonstrated the scale’s predictive validity: high-CTB individuals were more likely to report engaging in activities during the past month and year that followed directly from their beliefs (Study 5), act on their beliefs when given the opportunity (Study 6), and show more polarized attitudes toward ideologically-relevant groups (Study 7). These findings illustrate the utility of a dispositional approach for examining the extent to which people follow their beliefs.     

Domain-specificity and individual differences in worry

Worrying is generally perceived to be an undesirable mental state. An evolutionary approach suggests, however, despite the potential distress, worry may function to focus individuals’ attention on evolutionarily-relevant tasks. In the current study (N = 193), we demonstrated that participants’ primary worries were focused within domains central to reproductive success and mate-value. Furthermore, mating strategy predicted worries in the domains of social status and mating. Neuroticism, as an individual difference reflecting vigilance to threats, was correlated with worry about fitness-relevant but not fitness-irrelevant domains. The current study documents the first domain-specific assessment of worries and complements this analysis with intriguing individual difference predictors of worry.     

Individual differences in stress and fatigue in two field studies of driving

This paper reports the findings of two field studies of Australian drivers in which individual differences in stress and fatigue were investigated. In the first study, 58 professional drivers completed measures of mood, fatigue and other subjective stress state measures, before and after performing a prolonged driving trip. The results indicated that the scales were sensitive to increased fatigue following the driving trip, and correlated appropriately with Fatigue Proneness, a driver stress trait. In the second study, 104 non-professional drivers completed identical subjective stress state measures as the professional drivers, before and after performing a driving trip. Drivers completed a measure of driving-related stress traits, the Driver Stress Inventory (DSI), and a measure of coping, the Driving Coping Questionnaire (DCQ). Both measures were predictive of state response to driving, and the association between Fatigue Proneness and post-drive fatigue found in the first study was replicated. Findings from these studies suggest that fatigue and stress reactions to driving are psychometrically distinct, but may have some common antecedents, such as use of emotion-focused coping. The studies confirm the importance of fatigue and stress as potential safety problems, but also highlight the role of individual differences in response to the demands of driving.     

She works hard for the money: Valuing effort underlies gender differences in behavioral self-handicapping

Research in the area of self-handicapping has consistently demonstrated a robust yet puzzling gender difference in the use of and evaluation of behavioral self-handicaps; women (1) are less likely to use these forms of handicaps, particularly those involving the actual or reported reduction of effort, and (2) evaluate the use of these handicaps by others more negatively than do men. The present research examines several possible explanations for these consistent gender differences and finds that the personal value placed on effort is an important mediator of these effects.     

Individual differences in self-initiated processing at encoding and retrieval: A latent variable analysis

The current study examined individual differences in self-initiated processing (SIP) in memory tasks. Participants performed four memory tasks that varied the amount of SIP required at encoding, retrieval, or both as well as cognitive ability measures. It was found that the correlation between recall performance and cognitive abilities changed as a function of the amount of SIP required. Additionally, it was found that although both free and cued recall measures accounted for variance in cognitive abilities, only the free recall accounted for unique variance in cognitive abilities. It is suggested that the predictive power of a task is determined in part based on the amount of SIP required.     

Modeling individual differences using Dirichlet processes

We introduce a Bayesian framework for modeling individual differences, in which subjects are assumed to belong to one of a potentially infinite number of groups. In this model, the groups observed in any particular data set are not viewed as a fixed set that fully explains the variation between individuals, but rather as representatives of a latent, arbitrarily rich structure. As more people are seen, and more details about the individual differences are revealed, the number of inferred groups is allowed to grow. We use the Dirichlet process—a distribution widely used in nonparametric Bayesian statistics—to define a prior for the model, allowing us to learn flexible parameter distributions without overfitting the data, or requiring the complex computations typically required for determining the dimensionality of a model. As an initial demonstration of the approach, we present three applications that analyze the individual differences in category learning, choice of publication outlets, and web-browsing behavior.     

Working memory capacity and retrieval limitations from long-term memory: An examination of differences in accessibility

In two experiments, the locus of individual differences in working memory capacity and long-term memory recall was examined. Participants performed categorical cued and free recall tasks, and individual differences in the dynamics of recall were interpreted in terms of a hierarchical-search framework. The results from this study are in accordance with recent theorizing suggesting a strong relation between working memory capacity and retrieval from long-term memory. Furthermore, the results also indicate that individual differences in categorical recall are partially due to differences in accessibility. In terms of accessibility of target information, two important factors drive the difference between high- and low-working-memory-capacity participants. Low-working-memory-capacity participants fail to utilize appropriate retrieval strategies to access cues, and they also have difficulty resolving cue overload. Thus, when low-working-memory-capacity participants were given specific cues that activated a smaller set of potential targets, their recall performance was the same as that of high-working-memory-capacity participants.     

Barriers and Supports for Continuing in Mathematics and Science: Gender and Educational Level Differences

This article presents three studies that provide an in-depth examination of STEM-related supports and barriers. These studies constructed an instrument to identify male and female perceptions of the barriers and supports for pursuing coursework and/or careers in mathematics and sciences domains; to pilot test and refine that instrument; and then to explore gender differences in perceptions of supports and barriers at three different educational levels: middle school, high school, and college. Study 1 involved using literature reviews and in-depth interviews at the three educational levels to broadly identify perceived supports and barriers, and to develop a taxonomy of barrier and supports at each level. Based upon the taxonomy, study 2 involved the construction and pilot testing of a barriers and support instrument. Study 3 involved administering the revised instrument to a large sample of participants at each educational level. Results indicate both gender and developmental differences in perceptions of the barriers and supports for pursuing a math or science curriculum.     

Developmental analyses of individual differences in intelligence: Comments on Demetriou et al. (2013)

In this commentary, I mention strengths of the work reported by Demetriou et al. (2013), including sophisticated methods, a powerful integrative theory, and provocative findings. I also suggest ways in which this line of work could be extended, including extending the developmental trajectory, moving beyond tests and tasks, and exploring the full richness of individual variations.     

Impact of individual differences upon emotion-induced memory trade-offs

After seeing a scene containing an emotional component (e.g., a snake in a forest) people often demonstrate a “trade-off” in memory, where memory for the emotional component (e.g., the snake) is good, but memory for the non-emotional elements (e.g., the forest) is poor. The result is an incomplete memory retaining central emotional information at the expense of neutral background information. Though almost everyone demonstrates the trade-off, there may be individual differences in the magnitude of the effect. We investigated whether differences in the strength of the trade-off would correlate with anxiety levels, working memory capacity, and executive functioning abilities. Sixty-four participants studied scenes comprised of a negative or neutral item placed on a neutral background, and memory was later tested for items and backgrounds separately. The magnitude of the trade-off correlated positively with anxiety and negatively with visuospatial working memory and executive function. These results suggest that greater anxiety, poor visuospatial working memory, and poor executive function may inhibit formation of complete mental representations of these complex emotional scenes.     

Common and distinct factors in decision making under ambiguity and risk: A psychometric study of individual differences

The relation between decision making under ambiguity and risky decision making was examined. In Studies 1 and 2, choices under ambiguity were measured for a large sample receiving an Ellsberg-type Ambiguity-Probability Tradeoff Task. Participants with extreme scores were recruited for Part 2 of each study which consisted of a risky decision making task (Study 1) or a series of decisions under ambiguity in “real life” scenarios (Study 2). Despite a time gap of up to 2 months, individual differences in scores on Part 1 predicted scores on Part 2. In Study 3 participants received in a single session several risky decision making tasks, several measures of decision making under ambiguity, and several personality scales related to uncertainty and decision making style. Taken together, the findings support the existence of a stable dispositional trait to reduce uncertainty in decision making but also task-specific differences related to gains and losses.     

Exploring the Relationship between Psychopathy and Helping Behaviors in Naturalistic Settings: Preliminary Findings

This study examined the helping behavior of participants with high (High-P; 15 males, 13 females) and low (Low-P; 14 males, 16 females) psychopathic traits without their awareness. In the first of three tests, we found Low-P participants offered more help to an apparently lost female confederate than High-P participants. In the second test, High-P compared to Low-P males offered more help to an “injured” female experimenter, the reverse was true for females. In the third test, High-P compared to Low-P females offered more help to a female confederate who had apparently dropped papers they were carrying; whereas the reverse was true for males. Our preliminary findings indicate that context, gender and psychopathic traits interact and impact helping behavior.     

The role of working memory capacity in autobiographical retrieval: Individual differences in strategic search

Remembering previous experiences from one's personal past is a principal component of psychological well-being, personality, sense of self, decision making, and planning for the future. In the current study the ability to search for autobiographical information in memory was examined by having college students recall their Facebook friends. Individual differences in working memory capacity manifested itself in the search of autobiographical memory by way of the total number of friends remembered, the number of clusters of friends, size of clusters, and the speed with which participants could output their friends' names. Although working memory capacity was related to the ability to search autobiographical memory, participants did not differ in the manner in which they approached the search and used contextual cues to help query their memories. These results corroborate recent theorising, which suggests that working memory is a necessary component of self-generating contextual cues to strategically search memory for autobiographical information.     

Individual differences in spatial mental imagery

In this article, we report a new image-scanning paradigm that allowed us to measure objectively individual differences in spatial mental imagery—specifically, imagery for location. Participants were asked to determine whether an arrow was pointing at a dot using a visual mental image of an array of dots. The degree of precision required to discriminate “yes” from “no” trials was varied. In Experiment 1, the time to scan increasing distances, as well as the number of errors, increased when greater precision was required to make a judgement. The results in Experiment 2 replicated those results while controlling for possible biases. When greater precision is required, the accuracy of the spatial image becomes increasingly important—and hence the effect of precision in the task reflects the accuracy of the image. In Experiment 3, this measure was shown to be related to scores on the Paper Folding test, on the Paper Form Board test, and on the visuospatial items on Raven's Advanced Progressive Matrices—but not to scores on questionnaires measuring object–based mental imagery. Thus, we provide evidence that classical standardized spatial tests rely on spatial mental imagery but not object mental imagery.     

Individual differences in false memory from misinformation: Cognitive factors

This research investigated the cognitive correlates of false memories that are induced by the misinformation paradigm. A large sample of Chinese college students (N=436) participated in a misinformation procedure and also took a battery of cognitive tests. Results revealed sizable and systematic individual differences in false memory arising from exposure to misinformation. False memories were significantly and negatively correlated with measures of intelligence (measured with Raven's Advanced Progressive Matrices and Wechsler Adult Intelligence Scale), perception (Motor-Free Visual Perception Test, Change Blindness, and Tone Discrimination), memory (Wechsler Memory Scales and 2-back Working Memory tasks), and face judgement (Face Recognition and Facial Expression Recognition). These findings suggest that people with relatively low intelligence and poor perceptual abilities might be more susceptible to the misinformation effect.     

Dissociative style and individual differences in verbal working memory span

Dissociative style is mostly studied as a risk factor for dissociative pathology, but it may also reflect a fundamental characteristic of healthy information processing. Due to the close link between attention and working memory and the previous finding of enhanced attentional abilities with a high dissociative style, a positive relationship was also expected between dissociative style and verbal working memory span. In a sample of 119 psychology students, it was found that the verbal span of the high-dissociative group was about half a word larger than of the medium and low-dissociative groups. It is suggested that dissociative style may be one of only very few individual differences that is directly relevant to consciousness research.     

Working through the pain: Working memory capacity and differences in processing and storage under pain

It has been suggested that pain perception and attention are closely linked at both a neural and a behavioural level. If pain and attention are so linked, it is reasonable to speculate that those who vary in working memory capacity (WMC) should be affected by pain differently. This study compares the performance of individuals who differ in WMC as they perform processing and memory span tasks while under mild pain and not. While processing performance under mild pain does not interact with WMC, the ability to store information for later recall does. This suggests that pain operates much like an additional processing burden, and that the ability to overcome this physical sensation is related to differences in WMC.