Biomedical subjects

N C Waugh

Publications and source records attributed to N C Waugh.

6 recordsLinked to original sources

PubMed1978

Age-related differences in serial binary classification.

In a two-choice serial task, three groups of subjects with median ages of 37, 54, and 69 years pressed one response lever when the current signal was the same as its immediate predecessor in a sequence, and the other when it was not. Four classes of events-same signal/same response, same signal/different response, different signal/same response, different signal/different response-occurred equally often. The reaction times of subjects in the oldest group exceeded those of the two younger groups by a constant amount under all conditions; there was no evidence that stimulus or response repetition interacted with age. The data from all age groups support only the hypothesis that repeating a given signal is sufficient to produce the repetition effect in a choice reaction task.

Adult↗

PubMed1978

Age and familiarity in memory scanning.

Sixty-five healthy males (31 to 75 years old) memorized lists of six letters (familiar or unfamiliar organization). Letters were then presented singly, and subjects responded yes or no according to whether a given letter was in the memorized set. Subjects of all ages took longer to respond in the case of the unfamiliar list. This was disproportionately true for the oldest subjects, consistent with the idea that the age-related differences in the unfamiliar condition could not be wholly accounted for by psychomotor factors. The distributions of response latencies in the oldest groups had greater variance and skew.

Adult↗

PubMed1978

Retrieval time from different memory stores.

Two experiments were carried out to measure age-related differences in speed of error-free recall by normal adults. The major results were that: (a) the time taken to read a word aloud (retrieval from lexical memory) does not increase appreciably until subjects reach their 60s; (b) the time taken to recall a verbal item just attended to (retrieval from primary memory) increases steadily throughout the adult years, and most markedly between the sixth and seventh decades; and, (c) the time taken to recall recent verbal information outside the span of attention (retrieval from secondary memory) also increases as a function of chronological age, at a relatively rapid rate and most markedly between the fifth and sixth decades. The effects are independent of the number of stimulus-response alternatives.

Adult↗

PubMed1977

Age-related differences in naming latency.

Older people seem to have difficulty learning new materials, perhaps because it takes them longer to retrieve relevant encoding information from memory. To assess the effects of age on speed of retrieval, 60 healthy males from 25 to 74 were shown pictures of common objects they were to name aloud as quickly as possible. The older subjects took longer to name the pictured objects. This difference was minimized with practice or when the name was cued, but did not interact with word frequency. The pattern of results for healthy older subjects was not similar to that found by Wingfield for brain-damaged subjects.

Adult↗

PubMed1976

Effects of age and frequency of stimulus repetitions on two-choice reaction time.

Binary choice-reaction times for 123 males, 25-79 years of age, were obtained in a sequence of discrete trials in which the proportion of occasions that the same stimulus was presented twice in succession varied from .25, .50, and .75 or from .75, .50, and .25 over successive thirds of the sequence. Stimulus alternations were responded to more rapidly than stimulus repetitions by subjects in all age groups, especially in trial blocks with .75 alterations. The absolute differences in mean reaction time to stimulus alterations and repetitions increased with age. The results are consistent with the hypothesis that reaction times are affected both by pre-existing expectations for stimulus alternations as well as expectations for stimulus alternations or repetitions developed during the course of the experiment. Mean response latency as well as between- and within-subject variability in performance increased with age. Analyses of frequency distributions of the reaction times indicated that the psychomotor component of reaction time increases with age while the decision-making component becomes more variable.

Adult↗

PubMedDate not supplied

Does retention of order require verbal labelling?

Older and younger adults attended to lists of either pictures or words presented one at a time. At the end of each list, they attempted to recall the serial position of each member of the list. There was a pronounced effect of primacy. No recency was observed, however, except when the very last item was tested first. The usual pictorial superiority effect was abolished when pictures were drawn from a conceptually homogenous set. It was reinstated when pictures were conceptually distinctive. Number of errors on pictures was highly correlated with the judged similarity of the items in a list. The younger subjects' performance uniformly exceeded that of the older ones; but chronological age failed to interact with any experimental variable. The results imply that pictures need not be verbally labelled in order for their serial positions to be retained.

Adolescent↗