Biomedical subjects

L McDonough

Publications and source records attributed to L McDonough.

8 recordsLinked to original sources

PubMed1998

Studies in inductive inference in infancy.

Imitation of events was used to explore the inductive generalizations that 14-month-olds have made about animals, vehicles, and household artifacts. In Experiment 1 infants generalized domain-specific properties such as drinking to animals but not to vehicles, whereas they generalized domain-neutral properties such as going into a building to exemplars from both domains. The next four experiments showed that infants tend to interpret animal events very broadly, for example, construing a dog merely as a land animal rather than as a differentiated kind in its own right. Infants were somewhat more selective in their construals of vehicles. Experiment 6 showed that 14-month-olds also generalize "basic-level properties" very broadly. For example, they chose a pan to demonstrate drinking almost as often as a cup and fed a bone to a bird as often as to a dog. By 20 months, their selections narrowed appropriately for artifacts, but were still overgeneralized for natural kinds. The experiments indicate that infants tend to generalize their early experiences broadly across domains, often across exemplars that have a variety of different surface characteristics. The data suggest that it is the conceptual meaning of objects, rather than their physical features, that controls early associative learning.

Child Development↗

PubMed1998

On developing a knowledge base in infancy.

The development of conceptual categories from 7 to 11 months of age was explored in 5 experiments using an object-examination task. Infants in this age range categorized the global domains of animals, vehicles, and furniture. Plants and kitchen utensils were tested at 11 months, and these domains were also categorized. When 9-month-olds were tested on kitchen utensils, they did not categorize them. Subdivisions within the animal and furniture domains were also examined. Infants did not show any subcategorization of furniture. In the animal domain both 9- and 11-month-olds responded to the life-form distinction between dogs and birds, but they did not differentiate the mammal categories of dogs and cats until 11 months. This early organization of the conceptual system into global domains that become increasingly differentiated is discussed in relation to the adult conceptual system and its breakdown in semantic dementia.

Age Factors↗

PubMed1998

The role of semantic context and memory in the acquisition of novel nouns.

Three studies assessed the ability of 2-year-olds to use semantic context to infer the meanings of novel nouns and to retain those meanings a day later. In the first experiment, 24 2-year-olds heard novel nouns in sentences that contained semantically constraining verbs (e.g., "Mommy feeds the ferret"). They chose from a set of four novel object pictures to indicate the referent. Children learned a majority of the novel words. However, they occasionally failed to choose the correct object even when they understood the verb. Experiment 2 examined whether this was due to an inability to identify some of the pictures of novel objects. Experiment 3 tested 24 2-year-olds' memory for the newly learned nouns following a 24 hr delay and found significant retention. Results are discussed in terms of learning mechanisms that facilitate vocabulary acquisition in young children.

Age Factors↗

PubMed1997

Deficits, delays, and distractions: an evaluation of symbolic play and memory in children with autism.

Two experiments were conducted to evaluate symbolic-deficit and memory-deficit hypotheses to account for the cognitive problems seen in children with autism. Experiment 1 tested imitation, in immediate and deferred conditions, of familiar actions with different sets of objects representing the developmental progression from functional to symbolic play. The results showed that the autism group and both their receptive language and nonverbal IQ-matched controls imitated familiar actions with realistic objects (evidence for functional play) and placeholder objects (evidence for symbolic play) after delays ranging from 24 hr to 3 weeks. Experiment 2 tested familiar three-step event sequences in which a placeholder object was substituted for the second step in half the events. The results showed that the autism group remembered as many of the actions with the placeholder objects as their language-matched controls and as many correctly ordered sequences, a finding that supports a symbolic-delay (rather than deficit) hypothesis. These results were obtained in highly structured test situations and sharply contrast with the impairments seen in children with autism who are observed in naturalistic settings. Two interpretations of these findings are offered. First, structured test settings minimize distractions that typically occur in naturalistic settings that may interfere or disrupt symbolic play in children with autism. Second, the results are consistent with an executive function deficit in that the autistic group demonstrated more knowledge in the test settings than they demonstrate spontaneously in naturalistic ones.

Attention↗

PubMed1996

Drinking and driving don't mix: inductive generalization in infancy.

The traditional view of inductive generalization in infancy is that it rests on perceptual similarity; infants are said to form perceptually based categories, such as dogs and cats, and then to associate various properties with them. Superordinate-level inductions, such as generalizations about animals as a domain, have been considered to be more abstract and assumed to be a later achievement. Three experiments were conducted to investigate these issues, using 14-month-olds as subjects. We modeled various properties or actions appropriate to animals or to vehicles and then assessed whether infants were willing to generalize their imitations of these actions to different exemplars from the same and different domains. Contrary to the traditional view, we found that infants this age have generalized the properties of drinking and sleeping throughout the animal domain, and the properties of "being keyed" and "giving a ride" throughout the vehicle domain. These generalizations are constrained solely by the boundaries of the domains themselves and are not influenced by the perceptual similarity of exemplars within the domains.

Alcohol Drinking↗

PubMed1995

The deferred imitation task as a nonverbal measure of declarative memory.

We tested amnesic patients, patients with frontal lobe lesions, and control subjects with the deferred imitation task, a nonverbal test used to demonstrate memory abilities in human infants. On day 1, subjects were given sets of objects to obtain a baseline measure of their spontaneous performance of target actions. Then different event sequences were modeled with the object sets. On day 2, the objects were given to the subjects again, first without any instructions to imitate the sequences, and then with explicit instructions to imitate the actions exactly as they had been modeled. Control subjects and frontal lobe patients reproduced the events under both uninstructed and instructed conditions. In contrast, performance by the amnesic patients did not significantly differ from that of a second control group who had the same opportunities to handle the objects but were not shown the modeled actions. These findings suggest that deferred imitation is dependent on the brain structures essential for declarative memory that are damaged in amnesia, and they support the view that infants who imitate actions after long delays have an early capacity for long-term declarative memory.

Aged↗

PubMed1995

Long-term recall of event sequences in infancy.

The first experiment shows that 11-month-olds can encode novel causal events from a brief period of observational learning, and recall much of the information after 24 h. The second experiment, using both a longitudinal and a cross-sectional design, shows recall of the same events after a delay of 3 months. The infants remembered more individual actions than whole sequences, but reproduced many of the events in their entirety (and always in correct order) after the long delay. Although they also reproduced arbitrarily ordered events immediately after being shown them at 11 months, they began to forget them after 24 h and showed essentially no recall for this type of event after 3 months. The experiments not only indicate long-lasting memory for briefly experienced events in infancy, they also suggest that the factors that organize recall at this young age are similar to those found in older children and adults.

Association Learning↗

PubMed1994

Very long-term recall in infants: infantile amnesia reconsidered.

Subjects who had participated in a study on non-verbal recall before their first birthday returned to the laboratory one year later and were tested for recall of their previous visit. During their previous visit they had shown recall of both familiar and novel actions on a set of novel objects. However, after a year's delay, evidence for recall was found for the familiar actions only. One action in particular was responsible for this finding: feeding a teddy bear with a schematic bottle. The majority of the returning subjects who had been shown this action repeated it after a year, whereas none of the other returning subjects and few of the subjects in the control groups performed this action. The results indicate that young infants have the ability to recall an event both at 11 months of age and after a delay as long as one year. The finding that infants can recall during a period that later becomes inaccessible to memory is important to our understanding of infantile amnesia.

Analysis of Variance↗