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Biomedical subjects

E C Merrill

Publications and source records attributed to E C Merrill.

8 recordsLinked to original sources
PubMed1992

Degree of associative relatedness and sentence processing by adolescents with and without mental retardation.

Previous research has suggested that individuals with mental retardation are less likely than individuals without mental retardation to access and incorporate information about the relations between words of sentences in the representations of those sentences in memory (e.g., Merrill & Bilsky, 1990; Merrill & Jackson, in press). A cued recall study and a semantic verification study were conducted to determine whether the magnitude of this group difference could be made smaller by increasing the degree to which the words in the sentences were semantically related. In both experiments, individuals with mental retardation exhibited an ability to utilize contextual information to a greater extent when the words were related. In the highly related conditions, the differences between groups was virtually eliminated.

Adolescent↗
PubMed1992

Sentence processing by adolescents with and without mental retardation.

A more thorough test of the hypothesis that persons with mental retardation are less likely to construct semantically integrated representations of sentences that they hear than are subjects without mental retardation (Merrill & Bilsky, 1989; Merrill & Mar, 1987) was provided. A series of sentences were presented to adolescents with and without mental retardation. Their memory for the object nouns of the sentences was then tested when they were provided with either the subject noun, the verb, or the subject plus verb of the sentence as a retrieval cue. The two-word cue was relatively better if an integrated semantic representation was constructed. Manipulations included decreasing the processing time given to subjects (expected to inhibit the construction of integrated representations) and presenting a picture with the sentence (expected to facilitate the construction of integrated representations). The reduction in time decreased performance for the subjects without mental retardation to the level normally observed for those with mental retardation; presenting a picture increased performance of subjects with mental retardation to the level of comparison subjects. Results support the suggestion that previously observed differences in sentence processing between individuals with and without mental retardation may be due to differences in generating integrated representations of the sentences during processing.

Adolescent↗
PubMed1992

Attentional resource demands of stimulus encoding for persons with and without mental retardation.

Speed of encoding differences between individuals with and without mental retardation were examined to determine whether they stem from an automatically executed cognitive process or from encoding processes that require attentional resources. In Experiment 1, encoding functions were generated for physical identity and name identity encoding while subjects retained a full memory load or half memory load. Size of memory load influenced encoding times for all subjects. However, the pattern of group differences suggested that subjects with mental retardation allocated fewer attentional resources to encoding, even though encoding may require more of their resources for efficient execution. These conclusions were supported in Experiment 2, in which resource allocation was assessed using response times to auditory probes placed at various locations in the semantic encoding and decision task.

Adolescent↗
PubMed1990

Individual differences in the representation of sentences in memory.

A cued recall procedure was used to assess the nature of the memory representation that underlies the ability of mentally retarded and nonretarded individuals to remember single sentences. Mentally retarded, equal-CA, and equal-MA subjects listened to a list of sentences after which their ability to recall the object noun of the sentence was assessed when they were provided recall cues that contained (a) only the subject noun of the original sentence, (b) only the verb of the sentence, or (c) both the subject and verb. As expected, performance for all groups was best when they were provided the subject plus verb cue relative to the single word cues. In addition, the groups differed in the magnitude of this two-word cue advantage, with the retarded subjects exhibiting the smallest and the equal-CA subjects exhibiting the largest advantage. This finding reflects a difference in the degree to which mentally retarded and nonretarded individuals construct sentence representations that more precisely specify the meaning of the sentence through the integration of its constituents.

Adolescent↗
PubMed1988

Phasic alertness and differences in picture encoding speed.

The relation between physical identity and name identity encoding speed was assessed. Correlational analyses indicated that similar processes may be involved in the two types of encoding and, by implication, that differences between mentally retarded and nonretarded subjects' physical identity and name identity encoding speed may result from common factors. Also, we assessed the extent to which differences in preparation for the presentation of external stimuli may account for any observed differences in encoding speed. A difference between retarded and nonretarded subjects in preparation time was apparent; however, this difference did not influence encoding speed.

Adult↗
PubMed1987

Differences between mentally retarded and nonretarded persons' efficiency of auditory sentence processing.

Mentally retarded adolescents and MA-matched nonretarded children participated in three experiments designed to examine differences in language-processing efficiency. A compressed speech technique was used in Experiments 1 and 2. Experiment 3 relied on a sentence-picture verification procedure. Our results suggest that retarded and nonretarded individuals differ in the speed with which they are able to execute the semantic-analytic processes but not necessarily the phonological encoding processes that are involved in auditory language comprehension. In addition, the data suggest a possible group difference in the quality of the semantic representation encoded during sentence processing.

Adolescent↗
PubMed1985

Differences in semantic processing speed of mentally retarded and nonretarded persons.

A modified Sternberg choice-reaction time procedure was used to compare differences in the speed with which mentally retarded and nonretarded adults were able to retrieve recently stored information from short-term memory and process permanently stored semantic information. Results revealed that the retarded adults were slower than were the nonretarded adults in both domains of processing; the relative magnitude of "processing inefficiency" exhibited by the retarded subjects was quite similar across the two domains (47% and 57% as efficient as the nonretarded subjects in short-term and long-term memory processing, respectively). This similarity suggests that inefficient processing may represent a fundamental deficiency of retarded individuals resulting from the inefficient execution of some central processing mechanism.

Adult↗