An Integrated Model of Executive Functioning is Helpful for Understanding ADHD and Associated Disorders

OBJECTIVE

The aim of this study is to test the discriminative capacity of executive function (EF) tasks to better define the cognitive functioning of children with ADHD and comorbidities.

METHOD

One hundred four children were presented with a battery of new EF tasks and a rating scale filled out by parents.

RESULTS

Preliminary analysis of the neuropsychological tasks revealed the presence of five factors: Speed of Processing, Inhibition, Planning, Execution, and Retrospective Memory. All children with ADHD were impaired in Execution (a measure describing the capacity to achieve a goal). ADHD-only children were specifically impaired in Planning, while ADHD + reading disorder (RD) children were impaired in Speed of Processing and Retrospective Memory. Children with ADHD + oppositional defiant disorder (ODD) did not show impairment in any other EF domains. The five EF processes correlated with the EF Questionnaire.

CONCLUSION

The present study describes different cognitive profiles in children with ADHD with or without comorbid disorders using neuropsychological EF measures.

Revise and resubmit: how real-time parsing limitations influence grammar acquisition

We present the results from a three-day artificial language learning study on adults. The study examined whether sentence-parsing limitations, in particular, difficulties revising initial syntactic/semantic commitments during comprehension, shape learners' ability to acquire a language. Findings show that both comprehension and production of morphology pertaining to sentence argument structure are delayed when this morphology consistently appears at the end, rather than at the beginning, of sentences in otherwise identical grammatical systems. This suggests that real-time processing constraints impact acquisition; morphological cues that tend to guide linguistic analyses are easier to learn than cues that revise these analyses. Parallel performance in production and comprehension indicates that parsing constraints affect grammatical acquisition, not just real-time commitments. Properties of the linguistic system (e.g., ordering of cues within a sentence) interact with the properties of the cognitive system (cognitive control and conflict-resolution abilities) and together affect language acquisition.

Young children's learning of relational categories: multiple comparisons and their cognitive constraints

Relational categories are notoriously difficult to learn because they are not defined by intrinsic stable properties. We studied the impact of comparisons on relational concept learning with a novel word learning task in 42-month-old children. Capitalizing on Gentner et al. (2011), two, three or four pairs of stimuli were introduced with a novel relational word. In a given trial, the set of pairs was composed of either close or far pairs (e.g., close pair: knife1-watermelon, knife2-orange, knife3-slice of bread and knife4-meat; far pair: ax-evergreen tree, saw-log, cutter-cardboard, and knife-slice of bread, for the “cutter for” relation). Close pairs (2 vs. 3 vs. 4 pairs) led to random generalizations whereas comparisons with far pairs gave the expected relational generalization. The 3 pair case gave the best results. It is argued that far pairs promote deeper comparisons than close pairs. As shown by a control experiment, this was the case only when far pairs display well known associations.

Rule-based category use in preschool children

We report two experiments suggesting that development of rule use in children can be predicted by applying metrics of complexity from studies of rule-based category learning in adults. In Experiment 1, 124 3- to 5-year-olds completed three new rule-use tasks. The tasks featured similar instructions but varied in the complexity of the rule structures that could be abstracted from the instructions. This measure of complexity predicted children's difficulty with the tasks. Children also completed a version of the Advanced Dimensional Change Card Sorting task. Although this task featured quite different instructions from those in our "complex" task, performance on these two tasks was correlated, as predicted by the rule-based category approach. Experiment 2 predicted findings of the relative difficulty of the three new tasks in 36 5-year-olds and also showed that response times varied with rule structure complexity. Together, these findings suggest that children's rule use depends on processes also involved in rule-based category learning. The findings likewise suggest that the development of rule use during childhood is protracted, and the findings bolster claims that some of children's difficulty in rule use stems from limits in their ability to represent complex rule structures.

Low-SES children's eyewitness memory: the effects of verbal labels and vocabulary skills

This study examined the effects of the verbal labels procedure and vocabulary skills on low-socioeconomic status (SES) preschool children's eyewitness memory. Children (N = 176) aged 3-5 years witnessed a conflict event and were then questioned about it in either a standard or a verbal labels interview. Findings revealed that children with higher rather than lower vocabulary skills produced more complete and accurate memories. Children who were given the verbal labels interview recalled more information, which included both correct and incorrect details. Overall, the verbal labels procedure did not improve children's performance on direct questions, but children with low vocabulary skills answered direct questions more accurately if they were given the verbal labels interview than when they were not. Implications of the findings for memory performance of low-SES children are discussed.

The relationship between linguistic and non-linguistic cognitive control skills in bilingual children from low socio-economic backgrounds

The present study examined whether linguistic cognitive control skills were related to non-linguistic cognitive control skills in monolingual children (Study 1) and in bilingual children from low socio-economic status (SES) backgrounds (Study 2). Linguistic inhibitory control was measured using a grammaticality judgment (GJ) task in which children judged the grammaticality of sentences while ignoring their meaning. Non-linguistic inhibitory control was measured using a flanker task. Study 1, in which we tested monolingual English-speaking children, revealed that better inhibitory control skills, as indexed by the performance on the flanker task, were associated with improved performance on the GJ task. Study 2, in which we tested bilingual English-Spanish speaking children from low SES backgrounds, revealed that better non-linguistic inhibitory control skills did not yield better performance on the GJ task. Together, these findings point to a role of domain-general attention mechanisms in language performance in typically developing monolingual children, but not in bilingual children from low SES. Present results suggest that the relationship between linguistic and domain-general cognitive-control abilities is instantiated differently in bilingual vs. monolingual children, and that language-EF interactions are sensitive to language status and SES.

Early communicative gestures prospectively predict language development and executive function in early childhood

Using an epidemiological sample (N = 1,117) and a prospective longitudinal design, this study tested the direct and indirect effects of preverbal and verbal communication (15 months to 3 years) on executive function (EF) at age 4 years. Results indicated that whereas gestures (15 months), as well as language (2 and 3 years), were correlated with later EF (φs ≥ .44), the effect was entirely mediated through later language. In contrast, language had significant direct and indirect effects on later EF. Exploratory analyses indicated that the pattern of results was comparable for low- and not-low-income families. The results were consistent with theoretical accounts of language as a precursor of EF ability, and highlighted gesture as an early indicator of EF.

A developmental window into trade-offs in executive function: the case of task switching versus response inhibition in 6-year-olds

Good executive function has been linked to many positive outcomes in academic performance, health, and social competence. However, some aspects of executive function may interfere with other cognitive processes. Childhood provides a unique test case for investigating such cognitive trade-offs, given the dramatic failures and developments observed during this period. For example, most children categorically switch or perseverate when asked to switch between rules on a card-sorting task. To test potential trade-offs with the development of task switching abilities, we compared 6-year-olds who switched versus perseverated in a card-sorting task on two aspects of inhibitory control: response inhibition (via a stop signal task) and interference control (via a Simon task). Across two studies, switchers showed worse response inhibition than perseverators, consistent with the idea of cognitive trade-offs; however, switchers showed better interference control than perseverators, consistent with prior work documenting benefits associated with the development of executive function. This pattern of positive and negative associations may reflect aspects of working memory (active maintenance of current goals, and clearing of prior goals) that help children focus on a single task goal but hurt in situations with conflicting goals. Implications for understanding components of executive function and their relationships across development are discussed.

Age-related changes in error processing in young children: a school-based investigation

Growth in executive functioning (EF) skills play a role children's academic success, and the transition to elementary school is an important time for the development of these abilities. Despite this, evidence concerning the development of the ERP components linked to EF, including the error-related negativity (ERN) and the error positivity (Pe), over this period is inconclusive. Data were recorded in a school setting from 3- to 7-year-old children (N=96, mean age=5 years 11 months) as they performed a Go/No-Go task. Results revealed the presence of the ERN and Pe on error relative to correct trials at all age levels. Older children showed increased response inhibition as evidenced by faster, more accurate responses. Although developmental changes in the ERN were not identified, the Pe increased with age. In addition, girls made fewer mistakes and showed elevated Pe amplitudes relative to boys. Based on a representative school-based sample, findings indicate that the ERN is present in children as young as 3, and that development can be seen in the Pe between ages 3 and 7. Results varied as a function of gender, providing insight into the range of factors associated with developmental changes in the complex relations between behavioral and electrophysiological measures of error processing.

The role of stimulus novelty on children's inflexible dimensional switching

Children's ability to flexibly shift attention between different representational schemes was investigated using the dimensional change card sorting task. Across three experiments (N = 56 three-year-olds and N = 40 four-year-olds in ; N = 14 three-year-olds in ; and N = 14 three-year-olds in ) the role of perceptual information on children's cognitive flexibility was investigated by manipulating different aspects of the task materials between pre- and postswitch phases. Better performance was observed when either task-relevant (the color or shape of the images on the cards) or task-irrelevant information (the background color or shape of the actual cards) was changed, with this improvement occurring when the changes were salient enough to induce a stimulus novelty effect.

Interpretation of contrastive pitch accent in six- to eleven-year-old English-speaking children (and adults)

Both off-line and on-line comprehension studies suggest not only toddlers and preschoolers, but also older school-age children have trouble interpreting contrast-marking pitch prominence. To test whether children achieve adult-like proficiency in processing contrast-marking prosody during school years, an eye-tracking experiment examined the effect of accent on referential resolution in six- to eleven-year-old children and adults. In all age groups, a prominent accent facilitated the detection of a target in contrastive discourse sequences (pink cat → green cat), whereas it led to a garden path in non-contrastive sequences (pink rabbit → green monkey: the initial fixations were on rabbits). While the data indicate that children as young as age six immediately interpret contrastive accent, even the oldest child group showed delayed fixations compared to adults. We argue that the children's slower recovery from the garden path reflects the gradual development in cognitive flexibility that matures independently of general oculomotor control.

Adjective semantics, world knowledge and visual context: comprehension of size terms by 2- to 7-year-old Dutch-speaking children

The interpretation of size terms involves constructing contextually-relevant reference points by combining visual cues with knowledge of typical object sizes. This study aims to establish at what age children learn to integrate these two sources of information in the interpretation process and tests comprehension of the Dutch adjectives groot 'big' and klein 'small' by 2- to 7-year-old children. The results demonstrate that there is a gradual increase in the ability to inhibit visual cues and to use world knowledge for interpreting size terms. 2- and 3-year-old children only used the extremes of the perceptual range as reference points. From age four onwards children, like adults, used a cut-off point in the mid-zone of a series. From age five on, children were able to integrate world knowledge and perceptual context. Although 7-year-olds could make subtle distinctions between sizes of various object classes, their performance on incongruent items was not yet adult-like.

Why won't you do what I want? The informative failures of children and models

Computational models are powerful tools - too powerful, according to some. We argue that the idea that models can "do anything" is wrong, and describe how their failures have been informative. We present new work showing surprising diversity in the effects of feedback on children's task-switching, such that some children perseverate despite this feedback, other children switch as instructed, and yet others play an "opposites" game without truly switching to the newly-instructed task. We present simulations that demonstrate the failure of an otherwise-successful neural network model to capture this failure of children. Simulating this pattern motivates the inclusion of updating mechanisms that make contact with a growing literature on frontostriatal function, despite their absence in extant theories of the development of cognitive flexibility. We argue from this and other examples that computational models are more constrained than is typically acknowledged, and that their resulting failures can be theoretically illuminating.

The impact of scaffolding and overhearing on young children's use of the spatial terms between and middle

The primary goal was to specify the impact of scaffolding and overhearing on young children's use of the spatial terms between and middle. Four- and five-year-old children described the location of a mouse hidden between two furniture items in a dollhouse with assistance from a parent. Children's use of between and middle increased significantly across trials, and in concert, parents' directive scaffolding involving middle decreased across trials. In the second study, three common scaffolding types (Between Directive, Middle Directive, non-directive) were compared with a no prompt condition by having children receive prompts from a doll and with overhearing conditions in which children overheard conversations between two adult experimenters containing between or middle. Children's use of between and middle was much more frequent following directive prompting than following non-directive prompting, no prompting, or overhearing. Moreover, children showed some evidence of using between and middle in response to non-directive prompting and overhearing.

Putting theory of mind in its place: psychological explanations of the socio-emotional-communicative impairments in autistic spectrum disorder

In this review, the history of the theory of mind (ToM) theory of autistic spectrum disorder (ASD) is outlined (in which ToM is indexed by success on false belief tasks), and the explanatory power and psychological causes of impaired ToM in ASD are critically discussed. It is concluded that impaired ToM by itself has only limited explanatory power, but that explorations of the psychological precursors of impaired ToM have been fruitful in increasing understanding of mindreading impairments in ASD (where 'mindreading' refers those abilities that underlie triadic interaction as well as ToM). It is argued that early explanations of impaired mindreading are untenable for various reasons, but that impairments of dyadic interaction in ASD that could lead to impaired ability to represent others' mental states may be the critical psychological cause, or causes, of impaired ToM. The complexity of causal routes to impaired ToM is emphasized.

Refining the understanding of inhibitory processes: how response prepotency is created and overcome

Understanding (a) how responses become prepotent provides insights into when inhibition is needed in everyday life. Understanding (b) how response prepotency is overcome provides insights for helping children develop strategies for overcoming such tendencies. Concerning (a), on tasks such as the day-night Stroop-like task, is the difficulty with inhibiting saying the name of the stimulus due to the name being semantically related to the correct response or to its being a valid response on the task (i.e. a member of the response set) though incorrect for this stimulus? Experiment 1 (with 40 4-year-olds) suggests that prepotency is caused by membership in the response set and not semantic relation. Concerning (b), Diamond, Kirkham and Amso (2002) found that 4-year-olds could succeed on the day-night task if the experimenter sang a ditty after showing the stimulus card, before the child was to respond. They concluded that it was because delaying children's responses gave them time to compute the correct answer. However, Experiment 2 (with 90 3-year-olds) suggests that such a delay helps because it gives the incorrect, prepotent response time to passively dissipate, not because of active computation during the delay.

Comparing the performances of apes (Gorilla gorilla, Pan troglodytes, Pongo pygmaeus) and human children (Homo sapiens) in the floating peanut task

Recently, Mendes et al. [1] described the use of a liquid tool (water) in captive orangutans. Here, we tested chimpanzees and gorillas for the first time with the same "floating peanut task." None of the subjects solved the task. In order to better understand the cognitive demands of the task, we further tested other populations of chimpanzees and orangutans with the variation of the peanut initially floating or not. Twenty percent of the chimpanzees but none of the orangutans were successful. Additional controls revealed that successful subjects added water only if it was necessary to obtain the nut. Another experiment was conducted to investigate the reason for the differences in performance between the unsuccessful (Experiment 1) and the successful (Experiment 2) chimpanzee populations. We found suggestive evidence for the view that functional fixedness might have impaired the chimpanzees' strategies in the first experiment. Finally, we tested how human children of different age classes perform in an analogous experimental setting. Within the oldest group (8 years), 58 percent of the children solved the problem, whereas in the youngest group (4 years), only 8 percent were able to find the solution.

Source-specific oppositional defiant disorder among inner-city children: prospective prediction and moderation

We examined prospective prediction from parent- and teacher-reported oppositional defiant disorder (ODD) symptoms to parent-reported ODD, conduct disorder (CD), major depressive disorder (MDD), and generalized anxiety disorder symptoms and whether child executive functioning abilities moderated these relations among an urban, low-income sample of first- to third-grade children (N = 87). Time 1 parent-reported ODD predicted each Time 2 outcome. Time 1 teacher-reported ODD predicted Time 2 CD and MDD symptoms. After controlling for Time 1 co-occurring symptoms, only prediction from Time 1 teacher-reported ODD to CD and MDD symptoms remained significant. Child executive functioning abilities moderated relations between Time 1 parent-reported ODD and Time 2 ODD, and Time 1 teacher-reported ODD and Time 2 CD and MDD. Among children with better executive functioning abilities, higher Time 1 ODD was associated with higher Time 2 symptoms.

A computational account of children's analogical reasoning: balancing inhibitory control in working memory and relational representation

Theories accounting for the development of analogical reasoning tend to emphasize either the centrality of relational knowledge accretion or changes in information processing capability. Simulations in LISA (Hummel & Holyoak, 1997, 2003), a neurally inspired computer model of analogical reasoning, allow us to explore how these factors may collaboratively contribute to the development of analogy in young children. Simulations explain systematic variations in United States and Hong Kong children's performance on analogies between familiar scenes (Richland, Morrison & Holyoak, 2006; Richland, Chang, Morrison & Au, 2010). Specifically, changes in inhibition levels in the model's working-memory system explain the developmental progression in US children's ability to handle increases in relational complexity and distraction from object similarity during analogical reasoning. In contrast, changes in how relations are represented in the model best capture cross-cultural differences in performance between children of the same ages (3-4 years) in the United States and Hong Kong. We use these results and simulations to argue that the development of analogical reasoning in children may best be conceptualized as an equilibrium between knowledge accretion and the maturation of information processing capability.

A self-regulatory model of behavioral disinhibition in late adolescence: integrating personality traits, externalizing psychopathology, and cognitive capacity

Two samples with heterogeneous prevalence of externalizing psychopathology were used to investigate the structure of self-regulatory models of behavioral disinhibition and cognitive capacity. Consistent with expectations, structural equation modeling in the first sample (N=541) showed a hierarchical model with 3 lower order factors of impulsive sensation seeking, antisociality/unconventionality, and lifetime externalizing problem counts, with a behavioral disinhibition superfactor best accounted for the pattern of covariation among 6 disinhibited personality trait indicators and 4 externalizing problem indicators. The structure was replicated in a second sample (N=463) and showed that the behavioral disinhibition superfactor, and not the lower order impulsive sensation seeking, antisociality/unconventionality, and externalizing problem factors, was associated with lower IQ, reduced short-term memory capacity, and reduced working memory capacity. The results provide a systemic and meaningful integration of major self-regulatory influences during a developmentally important stage of life.

Reaching around barriers: the performance of the great apes and 3-5-year-old children

Inhibitory control has been suggested as a key predictive measure of problem-solving skills in human and nonhuman animals. However, there has yet to be a direct comparison of the inhibitory skills of the nonhuman apes and their development in human children. We compared the inhibitory skills of all great ape species, including 3-5-year-old children in a detour-reaching task, which required subjects to avoid reaching directly for food and instead use an indirect reaching method to successfully obtain the food. We tested 22 chimpanzees, 18 bonobos, 18 orangutans, 6 gorillas and 42 children. Our sample included chimpanzees, bonobos and orangutans housed in zoos (N = 27) and others housed in sanctuaries in their native habitats (N = 37). Overall, orangutans were the most skilful apes, including human children. As expected older children outperformed younger children. Sanctuary chimpanzees and bonobos outperformed their zoo counterparts whereas there was no difference between the two orangutan samples. Most zoo chimpanzees and bonobos failed to solve the original task, but improved their performance with additional training, although the training method determined to a considerable extent the level of success that the apes achieved in a transfer phase. In general, the performance of the older children was far from perfect and comparable to some of the nonhuman apes tested.

Children's (in)ability to recover from garden paths in a verb-final language: evidence for developing control in sentence processing

An eye-tracking study explored Korean-speaking adults' and 4- and 5-year-olds' ability to recover from misinterpretations of temporarily ambiguous phrases during spoken language comprehension. Eye movement and action data indicated that children, but not adults, had difficulty in recovering from these misinterpretations despite strong disambiguating evidence at the end of the sentence. These findings are notable for their striking similarities with findings from children parsing English; however, in those and other studies of English, children were found to be reluctant to use late-arriving syntactic evidence to override earlier verb-based cues to structure, whereas here Korean children were reluctant to use late-arriving verb-based cues to override earlier syntactic evidence. The findings implicate a general cross-linguistic pattern for parsing development in which late-developing cognitive control abilities mediate the recovery from so-called "garden path" sentences. Children's limited cognitive control prevents them from inhibiting misinterpretations even when the disambiguating evidence comes from highly informative verb information.

What do transitive inference and class inclusion have in common? Categorical (co)products and cognitive development

Transitive inference, class inclusion and a variety of other inferential abilities have strikingly similar developmental profiles—all are acquired around the age of five. Yet, little is known about the reasons for this correspondence. Category theory was invented as a formal means of establishing commonalities between various mathematical structures. We use category theory to show that transitive inference and class inclusion involve dual mathematical structures, called product and coproduct. Other inferential tasks with similar developmental profiles, including matrix completion, cardinality, dimensional changed card sorting, balance-scale (weight-distance integration), and Theory of Mind also involve these structures. By contrast, (co)products are not involved in the behaviours exhibited by younger children on these tasks, or simplified versions that are within their ability. These results point to a fundamental cognitive principle under development during childhood that is the capacity to compute (co)products in the categorical sense.

Children acquire various reasoning skills during a remarkably similar period of development. Yet, the reasons for these similarities are a mystery. Two examples are Transitive Inference and Class Inclusion, which develop around five years of age. Older children understand that if John is taller than Mary, and Mary is taller than Sue, then John is also taller than Sue. This form of reasoning is called transitive inference. Older children also understand that there are more fruits than apples. This inference is called class inclusion. We explain why these and a variety of other abilities show the same development using a branch of mathematics called category theory. Category theory reveals that they have related underlying structure. So, despite their apparent superficial differences these reasoning abilities have similar profiles of development because they involve related sorts of processes.