Sustained attention in language production: An individual differences investigation

Whereas it has long been assumed that most linguistic processes underlying language production happen automatically, accumulating evidence suggests that these processes do require some form of attention. Here we investigated the contribution of sustained attention: the ability to maintain alertness over time. In Experiment 1, participants’ sustained attention ability was measured using auditory and visual continuous performance tasks. Subsequently, employing a dual-task procedure, participants described pictures using simple noun phrases and performed an arrow-discrimination task while their vocal and manual response times (RTs) and the durations of their gazes to the pictures were measured. Earlier research has demonstrated that gaze duration reflects language planning processes up to and including phonological encoding. The speakers’ sustained attention ability correlated with the magnitude of the tail of the vocal RT distribution, reflecting the proportion of very slow responses, but not with individual differences in gaze duration. This suggests that sustained attention was most important after phonological encoding. Experiment 2 showed that the involvement of sustained attention was significantly stronger in a dual-task situation (picture naming and arrow discrimination) than in simple naming. Thus, individual differences in maintaining attention on the production processes become especially apparent when a simultaneous second task also requires attentional resources.     

Individual differences in the neural basis of causal inferencing

This study used fMRI to examine individual differences in the neural basis of causal inferencing. Participants with varying language skill levels, as indexed by scores on the vocabulary portion of the Nelson-Denny Reading Test, read four types of two-sentence passages in which causal relatedness (moderate and distant) and presence or absence of explicit clause connectives were orthogonally varied to manipulate coherence and cohesion during inference generation. Skilled readers showed better neural efficiency (less activation) during all context sentences and during all inference conditions. Increased activation in less-skilled readers was most extensively distributed in the right hemisphere (RH) homologues of left hemisphere (LH) language areas, especially in the most difficult passage types. Skilled readers also showed greater sensitivity to coherence (greater activation and synchronization in moderately related than distantly related passages) whereas less-skilled readers showed sensitivity to cohesion (greater activation and synchronization when clause connectives were present than when they were not). These finding support the hypothesis that skilled reading comprehension requires recruitment of the RH on an “as needed” basis. We describe the dynamic spillover hypothesis, a new theoretical framework that outlines the conditions under which RH language contributions are most likely evoked.     

Individual Differences in Learning Abilities Impact Structure Addition: Better Learners Create More Structured Languages

Over the last decade, iterated learning studies have provided compelling evidence for the claim that linguistic structure can emerge from non-structured input, through the process of transmission. However, it is unclear whether individuals differ in their tendency to add structure, an issue with implications for understanding who are the agents of change. Here, we identify and test two contrasting predictions: The first sees learning as a pre-requisite for structure addition, and predicts a positive correlation between learning accuracy and structure addition, whereas the second maintains that it is those learners who struggle with learning and reproducing their input who add structure to it. This prediction is hard to test in standard iterated learning paradigms since each learner is exposed to a different input, and since structure and accuracy are computed using the same test items. Here, we test these contrasting predictions in two experiments using a one-generation artificial language learning paradigm designed to provide independent measures of learning accuracy and structure addition. Adults (N = 48 in each study) were exposed to a semi-regular language (with probabilistic structure) and had to learn it: Learning was assessed using seen items, whereas structure addition was calculated over unseen items. In both studies, we find a strong positive correlation between individuals' ability to learn the language and their tendency to add structure to it: Better learners also produced more structured languages. These findings suggest a strong link between learning and generalization. We discuss the implications of these findings for iterated language models and theories of language change more generally.     

Use of phonetic specificity during the acquisition of new words: differences between consonants and vowels

The present study explores the issue of the use of phonetic specificity in the process of learning new words at 20 months of age. The procedure used follows Nazzi and Gopnik [Nazzi, T., & Gopnik, A. (2001). Linguistic and cognitive abilities in infancy: When does language become a tool for categorization? Cognition, 80, B11-B20]. Infants were first presented with triads of perceptually dissimilar objects, which were given made-up names, two of the objects receiving the same name. Then, word learning was evaluated through object selection/categorization. Tests involved phonetically different words (e.g. [pize] vs. [mora], Experiment 1), words differing minimally on their onset consonant (e.g. [pize] vs. [tize], Experiment 2a), and conditions which had never been tested before: non-initial consonantal contrasts (e.g. [pide] vs. [pige], Experiment 2b), and vocalic contrasts (e.g. [pize] vs. [pyze]; [pize] vs. [paze]; [pize] vs. [pizu], Experiments 3a-c). Results differed across conditions: words could be easily learnt in the phonetically different condition, and were learnt, though to a lesser degree, in both the initial and non-initial minimal consonant contrast; however, infants' global performance on all three vocalic contrasts was at chance level. The present results shed new light regarding the specificity of early words, and raise the possibility of different contributions for vowels and consonants in early word learning.     

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.     

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 category learning: sometimes less working memory capacity is better than more

We examined whether individual differences in working memory influence the facility with which individuals learn new categories. Participants learned two different types of category structures: rule-based and information-integration. Successful learning of the former category structure is thought to be based on explicit hypothesis testing that relies heavily on working memory. Successful learning of the latter category structure is believed to be driven by procedural learning processes that operate largely outside of conscious control. Consistent with a widespread literature touting the positive benefits of working memory and attentional control, the higher one’s working memory, the fewer trials one took to learn rule-based categories. The opposite occurred for information-integration categories - the lower one’s working memory, the fewer trials one took to learn this category structure. Thus, the positive relation commonly seen between individual differences in working memory and performance can not only be absent, but reversed. As such, a comprehensive understanding of skill learning - and category learning in particular - requires considering the demands of the tasks being performed and the cognitive abilities of the performer.     

Individual differences in the acceptance of stereotyping

Previous research has documented individual differences in a range of constructs relating to social stereotyping, prejudice, and intergroup attitudes. However, research has not sought specifically to measure a general acceptance of social stereotyping. In the present research, we explored attitudinal, cognitive, emotional, and personality correlates of a person’s self-reported willingness to rely on stereotypical information when interacting with people of different social and cultural groups. In six studies (N = 1080) we found that more acceptance of stereotyping was associated with more explicit and implicit stereotyping of particular groups, less liberal gender-role values, more authoritarian attitudes, preference for hierarchies, higher social dominance orientation, less universal outlook, less complexity in describing others’ emotions, less utilization of emotional information, and more utilization of social categories (gender and race) when rating the similarity of faces, less agreeable and more agentic personality, and more rigid and simplistic cognitive style (all independent of one’s gender). Female and African-American participants were less accepting of stereotyping than male and Caucasian participants. The general tendency to accept stereotyping in daily life is a measurable individual difference that may prove useful in social-personality research.     

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.     

Beyond quantity: Individual differences in working memory and the ordinal understanding of numerical symbols

In two different contexts, we examined the hypothesis that individual differences in working memory (WM) capacity are related to the tendency to infer complex, ordinal relationships between numerical symbols. In Experiment 1, we assessed whether this tendency arises in a learning context that involves mapping novel symbols to quantities by training adult participants to associate dot-quantities with novel symbols, the overall relative order of which had to be inferred. Performance was best for participants who were higher in WM capacity (HWMs). HWMs also learned ordinal information about the symbols that lower WM individuals (LWMs) did not. In Experiment 2, we examined whether WM relates to performance when participants are explicitly instructed to make numerical order judgments about highly enculturated numerical symbols by having participants indicate whether sets of three Arabic numerals were in increasing order. All participants responded faster when sequential sets (3-4-5) were in order than when they were not. However, only HWMs responded faster when non-sequential, patterned sets (1-3-5) were in order, suggesting they were accessing ordinal associations that LWMs were not. Taken together, these experiments indicate that WM capacity plays a key role in extending symbolic number representations beyond their quantity referents to include symbol-symbol ordinal associations, both in a learning context and in terms of explicitly accessing ordinal relationships in highly enculturated stimuli.     

Individual differences in the tendency to see the expected

Prior knowledge has been shown to facilitate the incorporation of visual stimuli into awareness. We adopted an individual differences approach to explore whether a tendency to ‘see the expected’ is general or method-specific. We administered a binocular rivalry task and manipulated selective attention, as well as induced expectations via predictive context, self-generated imagery, expectancy cues, and perceptual priming. Most prior manipulations led to a facilitated awareness of the biased percept in binocular rivalry, whereas strong signal primes led to a suppressed awareness, i.e., adaptation. Correlations and factor analysis revealed that the facilitatory effect of priors on visual awareness is closely related to attentional control. We also investigated whether expectation-based biases predict perceptual abilities. Adaptation to strong primes predicted improved naturalistic change detection and the facilitatory effect of weak primes predicted the experience of perceptual anomalies. Taken together, our results indicate that the facilitatory effect of priors may be underpinned by an attentional mechanism but the tendency to ‘see the expected’ is method-specific.     

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.     

Individual differences in the relationship between pleasure and arousal

The two fundamental dimensions assumed to underlie emotional experience—pleasure and arousal—are considered to be independent across individuals. We present evidence from an experience sampling study demonstrating that this independence does not necessarily hold when considering the affective experiences of a single individual. Participants (N = 80) reported how they were feeling in terms of pleasure and arousal nine times a day for seven days. The data showed that, although on average pleasure and arousal were independent, within-person pleasure–arousal associations substantially varied and ranged from strongly positive to strongly negative. This finding demonstrates that pleasant/unpleasant feelings usually co-occur with high arousal for some (reflecting joy/stress), but with low arousal for others (reflecting relaxation/sadness) and that persons differ in whether arousal is usually pleasant or unpleasant. These differences were found to be related to dispositional reward responsiveness, with high reward responsive individuals being characterized by a positive relation between pleasure and arousal and vice versa.     

Individual differences in autistic trait load in the general population predict visual working memory performance

Prior studies have reported instances of both intact and impaired working memory (WM) performance in people with autism spectrum disorder (ASD). In order to investigate the relation between autistic traits that extend into the normal population and WM, 104 normal college-aged students who varied in their levels of autistic traits were tested. The loading of ASD-associated traits in the normal population leads to differing predictions about WM performance. ASD traits related to a local processing style (or “attention to detail”) might enhance WM while ASD-associated traits related to difficulty switching attention and reorienting focus (or “social interaction”) might impair WM performance. To assess these predictions, participants filled out the Autism Spectrum Quotient (AQ) and performed a working memory task with both visual and verbal variants. AQ scores were then broken into “attention to detail” and “social interaction” factors, as proposed by Hoekstra and colleagues. The results showed that AQ scores did not predict verbal WM performance but they did predict visual WM performance. The social interaction and attention to detail factors of the AQ had opposing relationships with visual WM performance: A higher level of social difficulty was associated with significantly poorer visual WM performance while a higher level of attention to detail was associated with enhanced visual WM performance. Further investigation of the relation between AQ and WM using the original five-factor model proposed by Baron-Cohen and colleagues (2001) revealed an association between impoverished imagination and visual WM overall.     

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 the perception of similarity and difference

Thematically related concepts like coffee and milk are judged to be more similar than thematically unrelated concepts like coffee and lemonade. We investigated whether thematic relations exert a small effect that occurs consistently across participants (i.e., a generalized model), or a large effect that occurs inconsistently across participants (i.e., an individualized model). We also examined whether difference judgments mirrored similarity or whether these judgments were, in fact, non-inverse. Five studies demonstrated the necessity of an individualized model for both perceived similarity and difference, and additionally provided evidence that thematic relations affect similarity more than difference. Results suggest that models of similarity and difference must be attuned to large and consistent individual variability in the weighting of thematic relations.     

Individual differences in the acquisition of non‐linguistic audio‐visual associations in 5 year olds

Audio‐visual associative learning – at least when linguistic stimuli are employed – is known to rely on core linguistic skills such as phonological awareness. Here we ask whether this would also be the case in a task that does not manipulate linguistic information. Another question of interest is whether executive skills, often found to support learning, may play a larger role in a non‐linguistic audio‐visual associative task compared to a linguistic one. We present a new task that measures learning when having to associate non‐linguistic auditory signals with novel visual shapes. Importantly, our novel task shares with linguistic processes such as reading acquisition the need to associate sounds with arbitrary shapes. Yet, rather than phonemes or syllables, it uses novel environmental sounds – therefore limiting direct reliance on linguistic abilities. Five‐year‐old French‐speaking children (N = 76, 39 girls) were assessed individually in our novel audio‐visual associative task, as well as in a number of other cognitive tasks evaluating linguistic abilities and executive functions. We found phonological awareness and language comprehension to be related to scores in the audio‐visual associative task, while no correlation with executive functions was observed. These results underscore a key relation between foundational language competencies and audio‐visual associative learning, even in the absence of linguistic input in the associative task.     

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.     

Lexical quality and eye movements: Individual differences in the perceptual span of skilled adult readers

Two experiments used the gaze-contingent moving-window paradigm to investigate whether reading comprehension and spelling ability modulate the perceptual span of skilled adult readers during sentence reading. Highly proficient reading and spelling were both associated with increased use information to the right of fixation, but did not systematically modulate the extraction of information to the left of fixation. Individuals who were high in both reading and spelling ability showed the greatest benefit from window sizes larger than 11 characters, primarily because of increases in forward saccade length. They were also significantly more disrupted by being denied close parafoveal information than those poor in reading and/or spelling. These results suggest that, in addition to supporting rapid lexical retrieval of fixated words, the high quality lexical representations indexed by the combination of high reading and spelling ability support efficient processing of parafoveal information and effective saccadic targeting.