Individual differences in secondary task performance

The purpose of this research was to use secondary task performance as a predictor of performance on a difficult primary task. Reaction time (RT) to secondary probes that occurred during the rehearsal period of an easy memory task were used to measure spare capacity associated with the memory task. This measure was then correlated with performance on a harder version of the same memory task. Experiments 1-4 involved a paired associate memory task. Probe RT was sensitive to the difficulty of the paired associate task, and analysis of individual differences showed that probe RT during the easy version of the task was correlated with performance on a harder version of the task. Experiment 4 also utilized a spatial memory task. Probe RT was less sensitive to the demands of the spatial memory task, and in that case, the "easy-to-hard" prediction was not successful.     

Individual differences in sensory integration predict differences in time perception and individual levels of schizotypy

To interact functionally with our environment, our perception must locate events in time, including discerning whether sensory events are simultaneous. The Temporal Binding Window (TBW; the time window within which two stimuli tend to be integrated into one event) has been shown to relate to individual differences in perception, including schizotypy, but the relationship with subjective estimates of duration is unclear. We compare individual TBWs with individual differences in the filled duration illusion, exploiting differences in perception between empty and filled durations (the latter typically being perceived as longer). Schizotypy has been related to both these measures and is included to explore a potential link between these tasks and enduring perceptual differences. Results suggest that individuals with a narrower TBW make longer estimates for empty durations and demonstrate less variability in both conditions. Exploratory analysis of schizotypy data suggests a relationship with the TBW but is inconclusive regarding time perception.     

Individual differences and task format in sentence verification

This study examined the effects of task format and individual differences in cognitive ability on performance of the sentence-picture verification task. Four groups of subjects were selected on the basis of their scores on psychometric tests of verbal and spatial ability: low verbal/low spatial, high verbal/high spatial, low verbal/high spatial, and high verbal/low spatial. Subjects completed four different versions of the sentence verification task, each version differing in terms of the interval between sentence and picture presentation. The results confirmed the importance of both task format and spatial ability in determining the cognitive strategy employed by subjects in carrying out the task. The finding of principal interest, however, was that spatial ability was the most significant determinant of strategy choice, and that low spatial subjects made substantial use of linguistic strategies under task formats designed to encourage imaginal strategies.     

Individual differences in the acquisition of second language phonology

Perceptual training was employed to characterize individual differences in non-native speech sound learning. Fifty-nine adult English speakers were trained to distinguish the Hindi dental–retroflex contrast, as well as a tonal pitch contrast. Training resulted in overall group improvement in the ability to identify and to discriminate the phonetic and the tonal contrasts, but there were considerable individual differences in performance. A category boundary effect during the post-training discrimination of the Hindi but not of the tonal contrast suggests different learning mechanisms for these two stimulus types. Specifically, our results suggest that successful learning of the speech sounds involves the formation of a long-term memory category representation for the new speech sound.     

Individual differences in Sternberg’s memory scanning task

This study provides a new perspective on both the cognitive processes actually implemented and the effect of a simple experimental control - the recall constraint - in Sternberg’s memory scanning task. These findings were highlighted by adopting a new approach based on the comparison of qualitative and quantitative results.The analysis of individual processing, on 72 adults, each participating in one of two experimental conditions (with or without sequence recall), highlighted a large variability in quantitative results as well as qualitative procedures. Based on the participants’ retrospective verbalisations, two categories of strategies were identified: (1) the procedures used to memorize the sequence of digits, and (2) the procedures used to compare this sequence with the test digit, which includes strategies for coding the items and processes for searching them in memory. The analysis of the strategies shows that their frequencies of use depend not only on the experimental condition, but also on the participants, the level of task difficulty and the interaction between participants and level of difficulty. This variability questions the accuracy of Sternberg’s mean model. Furthermore, this approach suggests some answers to the old debate concerning the exhaustive search pattern for the yes response. Indeed, our results show three types of strategies that can be identified according to the different models of search suggested in the literature. The “exhaustive” search, that would only be involved in the recall condition and only for some of the participants, the “self-terminating” search and the “immediate” strategy, which can be identified with a model of parallel search with limited resources. Thus our study suggests that the different search models are appropriate but depend on both the specific experimental conditions and participant’s strategy. Our results should help to improve the interpretation of data collected with this paradigm in cognitive and neuroscientific studies of memory.     

Individual but not fragile: Individual differences in task control predict Stroop facilitation

The Stroop effect is composed of interference and facilitation effects. The facilitation is less stable and thus many times is referred to as a “fragile effect”. Here we suggest the facilitation effect is highly vulnerable to individual differences in control over the task conflict (between relevant color naming and irrelevant word reading in the Stroop task). We replicated previous findings of a significant correlation between stop-signal reaction time (SSRT) and Stroop interference, and also found a significant correlation between SSRT and the Stroop facilitation effect—participants with low inhibitory control (i.e., long SSRT) had no facilitation effect or even a reversed one. These results shed new light on the “fragile” facilitation effect and highlight the necessity of awareness of task conflict, especially in the Stroop task.     

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.     

Individual differences in field articulation as a factor in language comprehension

Previous research has suggested that performance differences associated with field independence/field articulation (FA) reflect differences in the efficiency of a limited capacity “working memory” (WM) system. An information-processing analysis of language comprehension suggests the involvement of WM. This experiment tested the hypothesis that performance differences in a language comprehension task could be predicted on the basis of level of FA and the mediating role of WM. Three levels of memory load were established by varying the logical structure of sets of semantically related sentences which subjects were required to integrate. In the low memory load condition, there was no difference between high and low FA subjects on a test of integration (inference) and specific memory (recognition). In the high memory load condition, there was a decline in performance for low FA subjects on both inference and recognition. Other aspects of the results suggested that the breakdown in information processing, for low FA subjects in the high memory load condition, occurred during or shortly after initial encoding of the sentences.     

Individual differences in children's emotion understanding: effects of age and language

Over the last two decades, it has been established that children's emotion understanding changes as they develop. Recent studies have also begun to address individual differences in children's emotion understanding. The first goal of this study was to examine the development of these individual differences across a wide age range with a test assessing nine different components of emotion understanding. The second goal was to examine the relation between language ability and individual differences in emotion understanding. Eighty children ranging in age from 4 to 11 years were tested. Children displayed a clear improvement with age in both their emotion understanding and language ability. In each age group, there were clear individual differences in emotion understanding and language ability. Age and language ability together explained 72% of emotion understanding variance; 20% of this variance was explained by age alone and 27% by language ability alone. The results are discussed in terms of their theoretical and practical implications.     

Individual differences in trait anxiety and goal-commitment predict updating efficiency on the reading span task

According to attentional control theory (ACT; Eysenck et al. in Emotion 7(2):336–353, 2007) anxious individuals recruit motivation on demanding tasks, which helps prevent performance shortfalls. We used a quasi-experimental design to examine the relationship between trait anxiety (operationalised using questionnaire scores), situational stress (manipulated using ego threat instructions) and motivation (indexed using a self-report goal-commitment scale) in predicting effectiveness (accuracy) and efficiency (accuracy divided by RT) on the reading span task. After controlling for depression, the variables were not related to effectiveness; however there was a significant trait anxiety × goal-commitment interaction on reading span efficiency. Higher trait anxiety predicted better efficiency at higher goal-commitment, and poorer efficiency at lower goal-commitment, and these relationships were independent of situational stress. Results are interpreted in terms of ACT.     

Individual differences in distancing responses to women on a photo choice task

A heterogeneous sample of adult women and men responded to a Photo Choice Task (PCT) in which they were asked to make 24 choices between two persons for a hypothetical interaction; eight of the choices were between a woman and a man. Participants also responded to a measure of adherence to Sex Role Stereotypes and to a measure of Adversarial Sexual Beliefs. On the eight choices between a woman and a man on the PCT, men over 30 and younger than 30 chose women below chance level. Women over 30 made other-gender and same-gender choices that did not differ from chance, but the women under 30 chose women over men reliably more than chance. Small but significant positive correlations were found among the scores on the PCT and the belief measures; for the total sample, the greater the choice of men over women for hypothetical interactions, the greater the agreement with sex role stereotypes and with adversarial sexual beliefs. An examination of mean differences in belief scores among groups of persons whose PCT scores (choice of men over women) were low, medium, and high revealed that men who were more likely to turn away from women in hypothetical situations were also more likely to adhere to stereotyped beliefs about sex roles and to view relationships between women and men as adversarial. This same pattern of individual differences was found among women but, for women, only the relationship between PCT scores and sex role stereotyping was significant.     

Individual differences of visual imagery ability in the benefit of a survival judgment task

This study investigated whether or not visual imagery ability affected the benefit of a survival judgment task. Based on the median split of their VVIQ score, 92 undergraduate students were classified as either high imagers (n = 46) or low imagers (n = 46). In the survival task, participants were requested to judge whether an item presented in the form of two Chinese characters was necessary or not in a survival situation. In the image judgment task, participants were requested to judge whether an item presented in the form of two Chinese characters arouses mental images or not. Participants were presented 18 concrete nouns at 4 s intervals in each condition. In both the survival judgment and the image judgment tasks, high imagers recalled more words than low imagers did. This result showed that imagery ability influenced the benefit of the survival judgment task. These results were discussed from the functional perspective of memory. Finally, we proposed the combination hypothesis, which combined elaboration and functional perspectives to explain the benefit of the survival judgment task.     

The role of schizotypy and creativity in a group problem-solving task

The well-studied link between psychotic traits and creativity is a subject of much debate. The present study investigated the extent to which schizotypic personality traits – as measured by O-LIFE (Oxford–Liverpool Inventory of Feelings and Experiences) – equip healthy individuals to engage as groups in everyday tasks. From a sample of 69 students, eight groups of four participants – comprised of high, medium, or low-schizotypy individuals – were assembled to work as a team to complete a creative problem-solving task. Predictably, high scorers on the O-LIFE formulated a greater number of strategies to solve the task, indicative of creative divergent thinking. However, for task success (as measured by time taken to complete the problem) an inverted U shaped pattern emerged, whereby high and low-schizotypy groups were consistently faster than medium schizotypy groups. Intriguing data emerged concerning leadership within the groups, and other tangential findings relating to anxiety, competition and motivation were explored. These findings challenge the traditional cliché that psychotic personality traits are linearly related to creative performance, and suggest that the nature of the problem determines which thinking styles are optimally equipped to solve it.     

Individual differences in working memory capacity and learning: Evidence from the serial reaction time task

High and low working memory (WM) capacity individuals performed the serial reaction time task under both incidental and intentional learning conditions to determine the role of WM capacity in the learning of sequential information. WM capacity differences emerged in conditions of intentional but not incidental learning, indicating that individual differences in WM capacity occur in tasks requiring some form of control, with little difference appearing on tasks that required relatively automatic processing. Furthermore, an index of learning was significantly related to a measure of general fluid intelligence under intentional conditions only. Thus, the degree of learning was significantly related to higher order cognition, but only when intentional processing was emphasized.     

Individual differences in resultant achievement motivation and latency to and persistence at an achievement task

Alternative hypotheses generated from the Atkinson (1957) and Atkinson and Feather (1966) risk-taking model of achievement motivation and the Atkinson and Birch (1970) dynamics of action theory comparing groups high and low in resultant achievement motivation (RAM) on latency to and persistence at an achievement task were tested. Subjects who had made two or more atypical shifts (choice of an easier task following success and choice of a more difficult task following failure) during 21 trials of a target-shooting game the first week were classified as low RAM (n=154), and subjects who had made 0 or 1 atypical shift were classified as high RAM (n=155). In week 2 subjects divided their time among two nonachievement tasks and the very easy, easy, intermediate, difficult, or most difficult levels of the achievement task. No main effects or interactions were found when latency to the achievement task was analyzed in a RAM by Difficulty level × Gender individual difference design. High-RAM subjects persisted significantly longer than low-RAM subjects across all conditions. Results are explained using the dynamic concepts of instigation, inhibition, and consummation. Analyses of sequential choices (week 1) among five difficulty levels did not support the Atkinson (1957) explanation of atypical shifts as avoidance of intermediate challenges for low-RAM subjects. Subjects who avoided the target-shooting game the second week more often persisted at the very easy task following success but not at the most difficult task following failure, results that are partially supportive of Feather's (1961) analysis of persistence.I wish to thank Dr. David Reuman, who suggested the research topic; the 24 undergraduate research assistants who ran subjects for this experiment; Rochelle Breitenbach, Laurie Colisanti, Kevin Kurkowski, Lee Ann McHenry, and Brenda Yee, who assisted with the data preparation and analyses; Ann Beck and Randi Gilbert, who provided editorial assistance; and Dr. Tilly Houtmans, who commented on an earlier version of this paper. A paper based on the dynamics of action research was presented at the Nags Head Conference on Motivation and Emotion on June 17, 1990. A paper based on the level of aspiration/achievement motivation results was presented at the Third International Meeting of the Society for the Advancement of Field Theory on September 16, 1988. A copy of the BASIC program for the Apple IIe computer is available to anyone who sends a 5 1/4-inch diskette.     

Individual differences in the shape bias in preschool children with specific language impairment and typical language development: theoretical and clinical implications

We investigated whether preschool children with specific language impairment (SLI) exhibit the shape bias in word learning: the bias to generalize based on shape rather than size, color, or texture in an object naming context (‘This is a wek; find another wek’) but not in a non‐naming similarity classification context (‘See this? Which one goes with this one?’). Fifty‐four preschool children (16 with SLI, 16 children with typical language [TL] in an equated control group, and 22 additional children with TL included in individual differences analyses but not group comparisons) completed a battery of linguistic and cognitive assessments and two experiments. In Experiment 1, children made generalization choices in object naming and similarity classification contexts on separate days, from options similar to a target object in shape, color, or texture. On average, TL children exhibited the shape bias in an object naming context, but children with SLI did not. In Experiment 2, we tested whether the failure to exhibit the shape bias might be linked to ability to detect systematicities in the visual domain. Experiment 2 supported this hypothesis, in that children with SLI failed to learn simple paired visual associations that were readily learned by children with TL. Analyses of individual differences in the two studies revealed that visual paired‐associate learning predicted degree of shape bias in children with SLI and TL better than any other measure of nonverbal intelligence or standard assessments of language ability. We discuss theoretical and clinical implications.