Individual Differences In Performance Research Articles

Individual differences in cocktail party listening: The relative role of decision weights and internal noise

A simulated “cocktail-party” listening experiment was conducted to determine the relative role of decision weights and internal noise in accounting for the large individual differences in performance typically observed in these experiments. The listener heard over headphones interleaved sequences of random vowels and were asked to judge on each trial whether the vowels were spoken by the same AAA or different ABA talkers. The A and B vowels had nominally different Fo and spatial position (simulated using Kemar HRTFs), but were randomly perturbed around these values on each presentation. Decision weights for each dimension, internal noise, and efficiency measures were estimated using COSS analysis [Berg (1990). J. Acoust. Soc. Am. 88, 149-158]. Decision weights were nonoptimal and differed across listeners, but weighting efficiency across individuals was quite similar. Individual differences in performance accuracy ranging over 40 percentage points were largely related to differences in internal noise. The...

Stimulus features affecting speech recognition in a two-talker masker

Large individual differences in performance have been observed for speech recognition in the presence of two-talker speech maskers. Moreover, two-talker masker samples appear to vary in masking effectiveness. These two observations suggest that (1) listeners vary in the extent to which they take advantage of stimulus features that aid in the segregation of target from masker speech and (2) maskers vary in the extent to which salient stimulus features are available that aid in the segregation of target from masker speech. Stimulus talker variability and individual listener variability are explored across two experiments. The first experiment evaluates differences between talkers based on vocal characteristics. These characteristics include fundamental frequency, pitch variability, and cadence. Additionally, listeners are asked to rank each individual competing talker’s voice with respect to similarity to the target talker’s voice. The second experiment will explore linguistic differences in the competing speech including two-talker maskers that consist of concatenated sentences, story passages, and conversational dialogs and how the content of the speech affects masking. Data will be presented for listeners with normal-hearing thresholds.

Talker variability in real-life speech recognition by cochlear implant users

For adult cochlear implant (CI) users, understanding speech in the real world, outside the clinic, can be challenging. A fundamental attribute of real-life speech is the immense amount of talker variability, present from multiple talkers with diverse linguistic and developmental histories. Talker variability, beyond background noise or competing talkers, contributes greatly to real-life, adverse listening conditions. Normal-hearing listeners are able to quickly and efficiently adapt to and learn talker differences to facilitate speech recognition in these conditions. However, talker variability may be particularly detrimental to CI users, since they must rely on signals that are inherently degraded, missing spectro-temporal details. In three experiments, we examined the impact of different sources of talker variability (talkers, accents, speaking styles) on CI speech recognition. The results showed that CI users have difficulty recognizing speech with vast talker variability, and discriminating talkers’ voices and accents, with a great amount of individual differences in performance. These findings suggest that the well-controlled, low-variability conditions in the lab or clinic may not reflect actual CI users’ performance in daily life. [Funding: VIDI Grant (No. 016.093.397) from the Netherlands Organization for Scientific Research (NWO), the Netherlands Organization for Health Research and Development (ZonMw).]

Unpacking symbolic number comparison and its relation with arithmetic in adults

Symbolic number – or digit – comparison has been a central tool in the domain of numerical cognition for decades. More recently, individual differences in performance on this task have been shown to robustly relate to individual differences in more complex math processing – a result that has been replicated across many different age groups. In this study, we ‘unpack’ the underlying components of digit comparison (i.e. digit identification, digit to number-word matching, digit ordering and general comparison) in a sample of adults. In a first experiment, we showed that digit comparison performance was most strongly related to digit ordering ability – i.e., the ability to judge whether symbolic numbers are in numerical order. Furthermore, path analyses indicated that the relation between digit comparison and arithmetic was partly mediated by digit ordering and fully mediated when non-numerical (letter) ordering was also entered into the model. In a second experiment, we examined whether a general order working memory component could account for the relation between digit comparison and arithmetic. It could not. Instead, results were more consistent with the notion that fluent access and activation of long-term stored associations between numbers explains the relation between arithmetic and both digit comparison and digit ordering tasks.

Visual Equivalence and Amodal Completion in Cuttlefish.

Modern cephalopods are notably the most intelligent invertebrates and this is accompanied by keen vision. Despite extensive studies investigating the visual systems of cephalopods, little is known about their visual perception and object recognition. In the present study, we investigated the visual processing of the cuttlefish Sepia pharaonis, including visual equivalence and amodal completion. Cuttlefish were trained to discriminate images of shrimp and fish using the operant conditioning paradigm. After cuttlefish reached the learning criteria, a series of discrimination tasks were conducted. In the visual equivalence experiment, several transformed versions of the training images, such as images reduced in size, images reduced in contrast, sketches of the images, the contours of the images, and silhouettes of the images, were used. In the amodal completion experiment, partially occluded views of the original images were used. The results showed that cuttlefish were able to treat the training images of reduced size and sketches as the visual equivalence. Cuttlefish were also capable of recognizing partially occluded versions of the training image. Furthermore, individual differences in performance suggest that some cuttlefish may be able to recognize objects when visual information was partly removed. These findings support the hypothesis that the visual perception of cuttlefish involves both visual equivalence and amodal completion. The results from this research also provide insights into the visual processing mechanisms used by cephalopods.

Influence of the SLC6A3-DAT1 Gene on Multifaceted Measures of Self-regulation in Preschool Children.

Development of self-regulation, the capacity to voluntarily modulate thoughts, emotions and actions is strongly related to the maturation of the dopamine-mediated executive attention network (EAN). The attention control processes associated with the EAN greatly overlap with efficiency of the executive functions and are correlated with measures of effortful control. Regulation of dopamine levels within the EAN, particularly in the basal ganglia is carried out by the action of dopamine transporters. In humans, the SLC6A3/DAT1 gene carries out the synthesis of the DAT protein. The 10-repeat allele has been associated with an enhanced expression of the gene and has been related to ADHD symptoms. Little is known about the impact of DAT1 variations on children's capacity to self-regulate in contexts that impose particular demands of regulatory control such as the school or home. This study defines a multi-domain phenotype of self-regulation and examines whether variations of the DAT1 gene accounts for individual differences in performance in 4–5 year old children. Results show that presence of the 10r allele is related to a diminished ability to exert voluntary regulation of reactivity. These findings shed light on the neurobiological mechanisms underlying individual differences in self-regulation during childhood.

Changes in the correlation between spatial and temporal source memory performance and BOLD activity across the adult lifespan

Studies investigating age-related functional differences associated with source memory have recently focused on the importance of clarifying the relationship between effects of age and performance on memory-related brain activations. One methodological challenge has been in discriminating between effects of age on memory-related brain activations that are independent from age-related differences in performance. In the current study, event-related functional magnetic resonance imaging (fMRI) was used to identify brain activity during spatial and temporal source encoding and retrieval across the adult lifespan. We used multivariate behavior partial least squares (B-PLS) to identify patterns of brain activity during source encoding and source retrieval that were associated with age and/or retrieval accuracy. The PLS analysis identified three significant effects. The first effect indicated that encoding and retrieval activity in fusiform, middle occipital–temporal and inferior parietal cortices increased with age and decreased with performance. The second effect showed that dorsolateral prefrontal cortex and limbic activity increased with age at encoding, and increased with performance at retrieval. The third effect indicated that activity in right ventrolateral prefrontal and bilateral hippocampus increased with age during retrieval and was differentially related to performance during encoding versus retrieval. We conclude that although some age-related differences in brain activity observed during source encoding and retrieval are associated with individual differences in performance, age-related differences in prefrontal and hippocampal areas exhibit more complex patterns of interactions between age, performance, and phase-related activity.

Human Exploration of Enclosed Spaces through Echolocation.

Some blind humans have developed echolocation, as a method of navigation in space. Echolocation is a truly active sense because subjects analyze echoes of dedicated, self-generated sounds to assess space around them. Using a special virtual space technique, we assess how humans perceive enclosed spaces through echolocation, thereby revealing the interplay between sensory and vocal-motor neural activity while humans perform this task. Sighted subjects were trained to detect small changes in virtual-room size analyzing real-time generated echoes of their vocalizations. Individual differences in performance were related to the type and number of vocalizations produced. We then asked subjects to estimate virtual-room size with either active or passive sounds while measuring their brain activity with fMRI. Subjects were better at estimating room size when actively vocalizing. This was reflected in the hemodynamic activity of vocal-motor cortices, even after individual motor and sensory components were removed. Activity in these areas also varied with perceived room size, although the vocal-motor output was unchanged. In addition, thalamic and auditory-midbrain activity was correlated with perceived room size; a likely result of top-down auditory pathways for human echolocation, comparable with those described in echolocating bats. Our data provide evidence that human echolocation is supported by active sensing, both behaviorally and in terms of brain activity. The neural sensory-motor coupling complements the fundamental acoustic motor-sensory coupling via the environment in echolocation.SIGNIFICANCE STATEMENT Passive listening is the predominant method for examining brain activity during echolocation, the auditory analysis of self-generated sounds. We show that sighted humans perform better when they actively vocalize than during passive listening. Correspondingly, vocal motor and cerebellar activity is greater during active echolocation than vocalization alone. Motor and subcortical auditory brain activity covaries with the auditory percept, although motor output is unchanged. Our results reveal behaviorally relevant neural sensory-motor coupling during echolocation.

Individual differences in performance on comprehension and knowledge tests with and without passages and questions

Several studies showed that reading comprehension items, which use a multiple-choice format, were solved above chance level even when the participants received only the response alternatives. In the present study, we pursued two goals. First, we examined whether similar results apply to measures of crystallized intelligence. Second, we investigated the structural equation model structure of performance on the original and manipulated tests. Based on a sample of 210 young adults, we replicated the finding that, even if only response options remain, participants perform above chance level on reading comprehension tests and extended these findings to performance on declarative knowledge tests. We found stable individual differences in performance on the manipulated measures with latent variables capturing shared variance in performance. These factors were strongly related with latent factors capturing shared variance in performance on the original test versions suggesting that general intellectual abilities are critical for performance on manipulated measures.

Contributions of Sensory Coding and Attentional Control to Individual Differences in Performance in Spatial Auditory Selective Attention Tasks.

Listeners with normal hearing thresholds (NHTs) differ in their ability to steer attention to whatever sound source is important. This ability depends on top-down executive control, which modulates the sensory representation of sound in the cortex. Yet, this sensory representation also depends on the coding fidelity of the peripheral auditory system. Both of these factors may thus contribute to the individual differences in performance. We designed a selective auditory attention paradigm in which we could simultaneously measure envelope following responses (EFRs, reflecting peripheral coding), onset event-related potentials (ERPs) from the scalp (reflecting cortical responses to sound) and behavioral scores. We performed two experiments that varied stimulus conditions to alter the degree to which performance might be limited due to fine stimulus details vs. due to control of attentional focus. Consistent with past work, in both experiments we find that attention strongly modulates cortical ERPs. Importantly, in Experiment I, where coding fidelity limits the task, individual behavioral performance correlates with subcortical coding strength (derived by computing how the EFR is degraded for fully masked tones compared to partially masked tones); however, in this experiment, the effects of attention on cortical ERPs were unrelated to individual subject performance. In contrast, in Experiment II, where sensory cues for segregation are robust (and thus less of a limiting factor on task performance), inter-subject behavioral differences correlate with subcortical coding strength. In addition, after factoring out the influence of subcortical coding strength, behavioral differences are also correlated with the strength of attentional modulation of ERPs. These results support the hypothesis that behavioral abilities amongst listeners with NHTs can arise due to both subcortical coding differences and differences in attentional control, depending on stimulus characteristics and task demands.

En psykolingvistisk test til kvantificering af progression i indlæringen af italiensk som fremmedsprog: metoder og resultater

This article describes a psycholinguistic protocol designed to elicit individual differences in performance regarding phonological (sound discrimination) and lexical (vocabulary memorization) aspects of learning Italian as a foreign language. An experiment built on that protocol revealed a wide range among participants regarding the number of novel vocabulary items memorized as well as a minor spread regarding the discrimination of a novel Italian consonant contrast. No correlation could be revealed between learning success in vocabulary acquisition and phonological discrimination. We conclude that the two types of tasks can be used as instruments for quantifying aspects of learning Italian as a foreign language.

Cognitive Abilities, Monitoring Confidence, and Control Thresholds Explain Individual Differences in Heuristics and Biases.

In this paper, we investigate whether individual differences in performance on heuristic and biases tasks can be explained by cognitive abilities, monitoring confidence, and control thresholds. Current theories explain individual differences in these tasks by the ability to detect errors and override automatic but biased judgments, and deliberative cognitive abilities that help to construct the correct response. Here we retain cognitive abilities but disentangle error detection, proposing that lower monitoring confidence and higher control thresholds promote error checking. Participants (N = 250) completed tasks assessing their fluid reasoning abilities, stable monitoring confidence levels, and the control threshold they impose on their decisions. They also completed seven typical heuristic and biases tasks such as the cognitive reflection test and Resistance to Framing. Using structural equation modeling, we found that individuals with higher reasoning abilities, lower monitoring confidence, and higher control threshold performed significantly and, at times, substantially better on the heuristic and biases tasks. Individuals with higher control thresholds also showed lower preferences for risky alternatives in a gambling task. Furthermore, residual correlations among the heuristic and biases tasks were reduced to null, indicating that cognitive abilities, monitoring confidence, and control thresholds accounted for their shared variance. Implications include the proposal that the capacity to detect errors does not differ between individuals. Rather, individuals might adopt varied strategies that promote error checking to different degrees, regardless of whether they have made a mistake or not. The results support growing evidence that decision-making involves cognitive abilities that construct actions and monitoring and control processes that manage their initiation.

Categorical Discrimination of Sequential Stimuli: All SΔ Are Not Created Equal

Pigeons were exposed to a novel variation of a stimulus discrimination task previously used with rats as a slot machine analog. We sought to replicate and extend characterizations of structural characteristics of responding, determine relations between those characteristics and identify predictors of individual differences in performance. Pecking during a “collect” phase produced food if and only if the keylight was red for the entire sample phase. In other trial types, the keylight was green, or started red and turned green after one or two pecks. The opportunity to respond was available for 5 s in all collect phases, permitting multiple responses per trial. Pigeons were less likely to peck in collect phases when sample stimuli were not all red, and when they did peck, it was at a lower rate. However, consistent with reactions to near wins in other slot machine tasks, there was more responding in collect phases that followed sample phases when the red keylight turned green after two pecks. Among initial response characteristics, response rate in trials that resembled near wins was the best predictor of terminal responding. Supporting their characterization as measures of stimulus control, collect proportions were negatively correlated with response times in the sample phase. Supporting their characterization as measures of conditioned reinforcing value, latency and response rate in collect phases were positively correlated, but neither was systematically correlated with proportion or sample phase response times. Ultimately, isolating measures of stimulus control and conditioned reinforcement may help determine the mechanisms responsible for near-win effects.

Tracking Multiple Statistics: Simultaneous Learning of Object Names and Categories in English and Mandarin Speakers.

Two experiments were conducted to examine adult learners' ability to extract multiple statistics in simultaneously presented visual and auditory input. Experiment 1 used a cross-situational learning paradigm to test whether English speakers were able to use co-occurrences to learn word-to-object mappings and concurrently form object categories based on the commonalities across training stimuli. Experiment 2 replicated the first experiment and further examined whether speakers of Mandarin, a language in which final syllables of object names are more predictive of category membership than English, were able to learn words and form object categories when trained with the same type of structures. The results indicate that both groups of learners successfully extracted multiple levels of co-occurrence and used them to learn words and object categories simultaneously. However, marked individual differences in performance were also found, suggesting possible interference and competition in processing the two concurrent streams of regularities.

Traits, cognitive processes and adaptation: An elegy for Hans Eysenck's personality theory

Hans Eysenck's personality theory has inspired several generations of researchers. However, it has substantial limitations as an account of the individual differences in performance and cognitive processing associated with personality traits. Three particular areas of concern are its handling of the complexity of processing, its attribution of performance effects to variation in cortical arousal, and its neglect of the adaptive significance of traits. The neurological concomitants of traits may be more consequential as indirect influences on skill acquisition than as direct influences on adaptation. Cognitive-adaptive theory provides a contrary perspective that sees traits as distributed across multiple processes and accommodates the dynamic nature of individual differences in adaptation. It may be time to laud the Eysenck theory for its historical contribution and lay it to rest with due respect.

Individual Differences in Performance on Comprehension and Knowledge Tests With and Without Passages and Questions

This paper fuses Lukes' (1974) three-dimensional view of power with the economic concept of informational asymmetry to explicate how access to information is organized and how power relationships arise from this organization. We argue that many observed asymmetries are deliberate and, drawing from the economics and finance literature, we posit that their outcomes are inevitably detrimental. The paper examines the techniques that foster information imbalances, such as media and propaganda, knowledge production, educational systems, legal and organizational structures, exclusive information networks, and surveillance. We conclude that in the absence of greater transparency, the deleterious effects of unequal access to information will continue and deepen. We further suggest that the analysis of the complexities of the issues warrants a broad, multidisciplinary approach and we suggest what this might include.

Validation of the Attention-Related Driving Errors Scale (ARDES) in an English-Speaking Sample.

The goal for this study was to develop an English translation of the Attention-Related Driving Errors Scale (ARDES-US) and to determine its potential relationship with driver history and other demographic variables. Individual differences in performance on vigilance and cognitive tasks are well documented, but less is known about susceptibility to attention-related errors while driving. The ARDES has been developed and administered in both Spanish and Chinese but to our knowledge has never been administered or examined in an English-speaking population. Two hundred ninety-six English-speaking individuals completed a series of self-report measures, including the ARDES-US, Attention-Related Cognitive Errors Scale, Mindful Attention Awareness Scale, and Cognitive Failures Questionnaire. A confirmatory factor analysis using maximum-likelihood estimates with robust standard errors revealed results largely consistent with previous versions of the ARDES, namely, the ARDES-Spain and ARDES-Argentina. Additionally, a number of new results emerged. Specifically, women, drivers who received traffic tickets within the previous 2 years, and those with a lower level of education all had a greater propensity toward self-reported driver inattention as measured by the ARDES-US. Further analyses revealed that these findings were independent of age, years of driving experience, and driving frequency. These results suggest that the ARDES-US is a valid and reliable measure of driver inattention with an English-speaking American sample. Potential applications of the ARDES-US include identifying individuals who are at greater risk of attention-related errors while driving and suggesting individually tailored training and safety countermeasures.

Arranging Objects in Space: Measuring Task-Relevant Organizational Behaviors During Goal Pursuit.

Human behavior unfolds primarily in built environments, where the arrangement of objects is a result of ongoing human decisions and actions, yet these organizational decisions have received limited experimental study. In two experiments, we introduce a novel paradigm designed to explore how individuals organize task-relevant objects in space. Participants completed goals by locating and accessing sequences of objects in a computer-based task, and they were free to rearrange the positions of objects at any time. We measure a variety of organization changes and evaluate how these measures relate to individual differences in performance. In Experiment 1, we show that with weak structure in task demands, changes in object positions that arise through performance of the task lead to improved order, characterized predominantly by a centralization of frequently used items and a peripheralization of infrequently used objects. In Experiment 2, with increased task structure, we observe more refined organizational tendencies, with selective contraction and clustering of interrelated task-relevant objects. We further demonstrate that these more selective organization behaviors are reliably associated with individual differences in task performance. Collectively, these two studies reveal properties of space and of task demands that support and facilitate effective organization of the environment in support of ongoing behavior.

Executive Function, Visual Attention and the Cocktail Party Problem in Musicians and Non-Musicians.

The goal of this study was to investigate how cognitive factors influence performance in a multi-talker, “cocktail-party” like environment in musicians and non-musicians. This was achieved by relating performance in a spatial hearing task to cognitive processing abilities assessed using measures of executive function (EF) and visual attention in musicians and non-musicians. For the spatial hearing task, a speech target was presented simultaneously with two intelligible speech maskers that were either colocated with the target (0° azimuth) or were symmetrically separated from the target in azimuth (at ±15°). EF assessment included measures of cognitive flexibility, inhibition control and auditory working memory. Selective attention was assessed in the visual domain using a multiple object tracking task (MOT). For the MOT task, the observers were required to track target dots (n = 1,2,3,4,5) in the presence of interfering distractor dots. Musicians performed significantly better than non-musicians in the spatial hearing task. For the EF measures, musicians showed better performance on measures of auditory working memory compared to non-musicians. Furthermore, across all individuals, a significant correlation was observed between performance on the spatial hearing task and measures of auditory working memory. This result suggests that individual differences in performance in a cocktail party-like environment may depend in part on cognitive factors such as auditory working memory. Performance in the MOT task did not differ between groups. However, across all individuals, a significant correlation was found between performance in the MOT and spatial hearing tasks. A stepwise multiple regression analysis revealed that musicianship and performance on the MOT task significantly predicted performance on the spatial hearing task. Overall, these findings confirm the relationship between musicianship and cognitive factors including domain-general selective attention and working memory in solving the “cocktail party problem”.

The Relationship Between Deliberate Practice and Performance in Sports

Why are some people more skilled in complex domains than other people? According to one prominent view, individual differences in performance largely reflect individual differences in accumulated amount of deliberate practice. Here, we investigated the relationship between deliberate practice and performance in sports. Overall, deliberate practice accounted for 18% of the variance in sports performance. However, the contribution differed depending on skill level. Most important, deliberate practice accounted for only 1% of the variance in performance among elite-level performers. This finding is inconsistent with the claim that deliberate practice accounts for performance differences even among elite performers. Another major finding was that athletes who reached a high level of skill did not begin their sport earlier in childhood than lower skill athletes. This finding challenges the notion that higher skill performers tend to start in a sport at a younger age than lower skill performers. We conclude that to understand the underpinnings of expertise, researchers must investigate contributions of a broad range of factors, taking into account findings from diverse subdisciplines of psychology (e.g., cognitive psychology, personality psychology) and interdisciplinary areas of research (e.g., sports science).