Biomedical subjects
Publications and source records attributed to R Kail.
In this article, I argue that most of the claims made by Morrison, Morrison, and Keating (1992) do not undermine the key results of the Kail (1988) study and that, contrary to their claims, the evidence still provides support for the original conclusion that a global mechanism is implicated in age-related change in speed of processing.
On measures of speeded performance, persons with mental retardation typically respond more slowly than do those without mental retardation. A review of 45 published studies yielded 518 pairs of response times (RTs) in which each pair consisted of a mean RT for a group of persons with mental retardation for an experimental condition and the corresponding mean RT for a group of persons without mental retardation. The primary result was that RTs of individuals with mental retardation increased linearly as a function of RTs for persons without mental retardation in corresponding conditions. These results are consistent with the view that differences in processing speed between persons with and without mental retardation reflect some general (i.e., nontask specific) component of cognitive processing. Possible candidates for the general component were discussed.
In two experiments, 9- and 10-year-olds and adults were tested on a mental rotation task in which they judged whether stimuli presented in different orientations were letters or mirror-images of letters. The mental rotation task was performed alone on 48 trials and concurrently with a memory task on 48 additional trials. The concurrent memory task in Experiment 1 was recalling digits; in Experiment 2, recalling positions in a matrix. The key result was that the slope of the function relating response time to stimulus orientation was the same when the mental rotation task was performed alone and when performed concurrently with the memory task. This result is interpreted as showing that mental rotation is an automatic process for both children and adults.
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Throughout childhood and adolescence, there are consistent age differences in speed of processing. Here 72 published studies yielded 1,826 pairs of response times (RTs) in which each pair consisted of adults' mean RT for a condition and the corresponding mean RT for a younger group. The primary results were that (a) children's and adolescents' RTs increase linearly as a function of adult RTs in corresponding conditions and (b) the amount of increase becomes smaller with age in a manner that is well described by an exponential function. These results are consistent with the view that age differences in processing speed reflect some general (i.e., nontask specific) component that changes rapidly during childhood and more slowly during adolescence. Possible candidates for the general component are discussed.
We tested 11- and 20-year-olds on 3360 trials of a mental rotation task in which they judged if stimuli presented in different orientations were letters or mirror images of letters. Children's and adults' processing times decreased substantially over practice. These changes were well characterized by hyperbolic and power functions in which most of the parameters of those functions were constrained to adults' values. Performance on two transfer tasks, mental rotation of letter-like characters and memory search for numbers, indicated that the practiced skill did not generalize to other domains. The results are discussed in terms of different mechanisms that might be responsible for the impact of practice.
In Experiment 1, 8- to 21-year-olds were tested on a visual search task in which they determined whether a target digit was present in a set of one to five digits and a memory search task in which they determined whether a target digit was a member of a previously presented set of one to five digits. Increases with age in speeds of visual and memory search were both described well by exponential functions, and the rate of developmental change was similar for the two processes. In Experiment 2, 8- to 22-year-olds were tested on a memory search task, a mental rotation task in which they judged whether a stimulus presented in various orientations was a letter or a mirror image of a letter, an analogical reasoning task in which they judged whether sets of pictures were related to one another according to the same rule, and a mental addition task in which they judged the accuracy of problems such as 2 + 3 = 6. Here, too, for three of the four tasks developmental change was described well by exponential functions with a common rate of change. Results are interpreted in terms of a central mechanism that limits speeded performance and that changes with age.
In this article, I show that many of Stigler et al.'s criticisms of my 1986 article are incorrect or based on assumptions that are implausible. I agree with their conclusion, however, that theories of cognitive development must include both domain-specific and general processes.