Frederick J. Morrison

Developmental differences in the allocation of processing capacity

Abstract Recently psychologists have formulated a comprehensive view of attention involving allocation of processing capacity. Although developmental changes in processing capacity have been proposed as one source of age differences in certain cognitive skills, there has been little systematic investigation of this hypothesis. In the present study, second and sixth graders and adults (8, 12, and 20 years of age, respectively) performed a letter-matching task (primary task) concurrently with an auditory detection task (secondary task). Changes in reaction time in the secondary task as a function of manipulations of the primary task were used to estimate capacity allocation to the primary task. Primary task variables included stage of processing (alerting, encoding, rehearsing, responding) and matching condition (physical-identity vs name-identity matching). Age differences in secondary task performance were found to be related to stage of processing but not to matching condition. Earlier stages of the letter match task (alerting, encoding) required somewhat more capacity allocation in younger subjects. Later stages (rehearsing, responding) made substantially higher demands on capacity in children. Capacity allocation may be an important cognitive variable mediating developmental differences in basic information processing skills, and may underlie age trends found in performance of certain complex cognitive tasks.

Cognitive Processes and Reading Disability: A Critique and Proposal

The search for the underlying nature and cause (s) of specific reading disability has proceeded for almost a century. At different times reading-disabled children have been described as suffering from a variety of specific cognitive deficits, from perceptual to attentional to memory problems. However, the explanation of this puzzling disorder has eluded investigators to the point where some are claiming that no satisfactory unitary set of principles can be found to explain the problems of all reading-disabled children (e.g., Applebee, 1971). Implicit in such claims is an admission of the inadequacy of current conceptualizations of the disorder.

Reading Disability: A Deficit in Rule Learning?

In recent years interest has grown among experimental, educational, and developmental psychologists in the mechanisms underlying individual differences in reading fluency (e.g., Carr, 1981; Perfetti & Lesgold, 1978; Stanovich, 1982a,b; Vellutino, 1979). One of the more puzzling questions under study is the source of reading problems among children with specific reading disability, or developmental dyslexia.

Paired associate learning in reading-disabled children: Evidence for a rule-learning deficiency

Two experiments examined whether normal and disabled readers differed in the utilization of rules in a paired associate learning task. Experiment 1 required children to learn symbol-word associates. Children were assigned to one of three conditions: nonrule, consistent rule, or inconsistent rule. When present, the rule was based on semantic opposites. Subjects benefited from having the rule, but disabled readers showed less improvement across four test blocks than both chronological age (CA) controls and reading age (RA) controls, particularly in the inconsistent condition. Experiment 2 required subjects to learn symbol-symbol associations in one of three conditions: nonrule, consistent rule, or inconsistent rule. When present, the rule specified the locations of a subsidiary figure in each symbol according to the pattern top-right, bottom-left. Disabled and normal readers did not differ in the nonrule condition where reliance on visual memory would be an effective strategy. Normal readers were superior to disabled readers in both rule conditions. In addition, disabled readers in the inconsistent rule condition were less able than normal readers to apply the rule in a generalization task where memory demands were reduced. Results supported the hypothesis that disabled readers have greater difficulty than normal readers inducing and/or using rules, particularly when they are inconsistent. It is suggested that difficulties in acquiring or using complex and inconsistent rules may be one important source of problems learning spelling-sound correspondence rules, which in English are complex and inconsistent.

Reading disability: A problem in rule learning and word decoding☆

Abstract Traditional explanations of reading disability (e.g., perceptual, memory, and phonetic receding deficits) have encountered logical difficulties and substantial empirical disconfirmation. An alternative conceptualization of the nature of reading disability is proposed. Disabled readers are hypothesized to suffer a fundamental problem in acquiring word knowledge and word processing skills. Poor decoding skills prevent them from developing sophisticated reading comprehension skills. From this perspective, the cognitive deficits of disabled readers result from failure to acquire and generalize complex processing skills originally mastered through reading experience. Recent research of the author and of others relating to these issues is discussed.

Processing of identity and position information in normal and disabled readers

Abstract Processing of identity and position information was investigated in normal and disabled readers at two grade levels (third/fourth grade and sixth grade). Two partial-report tasks were used. The identity task consisted of visual presentation of a five-letter array, followed by a probe letter. Subjects responded yes for a match and no for a mismatch (identity response). The identity + position task was identical except that an additional response was required on correct yes trials: subjects reported the position of the probe letter in the array (position response). Both grade level and reading ability differences were found on the identity response measure, but not on the position response measure. Results were inconsistent with the hypothesis that disabled readers have difficulties in processing order information. Reader ability differences in identity processing attenuated somewhat with age. Serial position functions for both identity and position responses suggested the presence of a left-to-right scanning operation in both age and ability groups. Reader ability differences in processing letter identities were discussed in the context of current theories of reading acquisition.

Word Decoding and Rule-Learning in Normal and Disabled Readers

Learning to decode words accurately and rapidly represents a major problem for the reading-disabled child. Recent advances in our understanding of word knowledge and decoding permit an assessment of those aspects of words that appear to be most troublesome to the disabled reader. A series of experiments is described; rule-based and word-specific views of decoding are examined. Results reveal that inconsistent rules and words are differentially harder for disabled readers than for normal readers. Additional evidence suggests that disabled readers may suffer a primary problem in learning irregular rule systems.

The Development of Alertness.

Abstract Two experiments explored variation in the alerting process across age and warning interval as well as the effects of alertness on subsequent processing. Experiment 1 obtained alertness functions for a group of 5-year-olds, 8-year-olds, and adults. Results revealed strong age differences in speed of alerting and in maintenance of alertness over a 1-sec interval. Five-year-olds alerted more slowly than older groups and sustained optimal alertness less well. Both groups of children showed more variability in alerting functions compared with adults. Experiment 2 examined the degree to which age differences in processing speed were attributable to differential speed and maintenance of alerting. Masking functions obtained across variations in the alerting interval revealed that when level of alertness was optimal in both 5-year-olds and adults, minimal age differences in processing speed were observed. During short, nonoptimal alerting intervals, speed of processing in adults was faster than in 5-year-old children. The pattern of results across studies suggested that alertness can fluctuate over time in young children, that level of alertness affects subsequent perceptual processing speed, and that developmental variation in speed and maintenance of alertness can partly explain observed age differences in processing speed. The potential role of alertness in more complex cognitive tasks is discussed.

Age trends in recognition memory for pictures: The effects of delay and testing procedure

Experiment 1 examined the effects of three delay intervals (0, 24, and 48 h) on recognition memory performance of 5-, 8-, and 11-year-olds and adults using a forced-choice procedure. Results revealed significant drops in performance after 24 h for 5-year-olds and after 48 h for 8-year-olds, with no performance decrement for older age groups. However, observations made during the first experiment raised the possibility that performance in the forced-choice procedure may have been biased, since subjects could infer which item was presented previously from high confidence that the new item had never been presented. Since age differences in use of this inferential process may have exaggerated the performance differences observed with the forced-choice procedure, Experiment 2 employed a single-item yes-no testing procedure to assess age and delay effects on recognition memory. Performance increased with age and decreased with delay, but no differential performance decrement occurred across delay as a function of age. Together, results confirmed earlier studies in demonstrating age invariance in information loss across time.

Is semantic interference really automatic

Interference in picture naming by task-irrelevant words in Stroop-like paradigms has been interpreted as evidence of automatic semantic processing of unattended words. However, this effect may have been due to attentional rather than automatic processing. To test this hypothesis, subjects were instructed either to ignore task-irrelevant words (selective attention) or to attend to them (divided attention). Three separate dependent measures (interference in picture naming, recognition memory, and confidence ratings) provided converging evidence about subjects’ attentional strategies. It was predicted that semantic interference would occur in the divided attention condition, but not when subjects attended selectively to the picture and ignored the word. Contrary to predictions, semantic interference occurred in both instruction conditions. Implications for future research on automaticity are discussed.