CLUSTERING IN MUSIC: AN APPRAISAL OF TASK FACTORS*

The pitch and temporal intervals of tune fragments, taken from folk music, were analyzed in terms of gestalt similarity principles and studied as determinants of music grouping structure. In experiment 1, the listeners were required to divide each tune into its ‘natural’ parts. Their ability to segment the tunes closely matched the boundaries generated by the clustering determinants under study, this consistency being particularly high for musicians. In experiment 2, a probe recognition task was used in which subjects were presented with a tune fragment followed by a true or false probe; true probes fell either within or across the boundaries studied in experiment 1. Since the probe was presented after the tune fragment, the differential ease of verifying within and across probes was taken to reflect the part structure of the tune held in memory. In order to study the part structure representation that is being built during music listening, a third experiment was devised by presenting the probe prior to the tune fragment and having subjects monitor the probe while listening to the fragment. Of the last two paradigms, only the latter was found to be sensitive to cluster boundaries, as defined along the temporal dimension. The entire set of results suggests that there does not seem to be a basic format of musical representation that is uniquely specified from the output of the clustering process.     

Dichotic perception and laterality in neonates

Groups of 4-day-old neonates were tested for dichotic discrimination and ear differences with the High-Amplitude-Sucking procedure. In the first experiment, dichotic speech discrimination was attested by comparison with a control group. Furthermore, among those subjects who showed a substantial recovery of sucking response at least after one of the two syllable changes, it was observed that significantly more subjects manifested a stronger reaction to a right-ear change than to a left-ear change. In the second experiment, 4-day-old neonates were tested on syllable and music timbre discrimination. The significant Stimulus Type x Ear interaction observed suggests perceptual asymmetries indicative of very precocious brain specialization.     

A critical reappraisal of the evidence for unconscious abstraction of deterministic rules in complex experimental situations

In a recent experiment (Lewicki et al., 1988) subjects were submitted to a four-choice RT paradigm for 3600 trials. On each of the successive logical blocks of five trials, the first two locations of the target were randomly distributed, and the last three locations were determined by complex rules. Although subjects were unable to verbalize the actual nature of the manipulation, performance on the last trials of each block improved at a faster rate and was better overall than performance on the first trials. In addition, subsequent rules changes on 480 additional trials only affected performance on the last three trials of each block. The present paper demonstrates that contrary to Lewicki et al's assertions this performance pattern requires neither acquisition of tacit knowledge of the composition rules, nor partitioning by the subjects of the sequence into logical blocks of five trials. Rather, the results can be accounted for by the relative frequency of a few simple sequences of target locations. Moreover, this alternative explanation alone correctly anticipates some striking features of fine-grained performance (Lewicki et al., 1988). The discussion focuses on methodological implications of these findings for investigation of unconscious learning, and speculates on what and how people learn when they encounter a complex and structured situation.     

Children’s memory for sentences and word strings in relation to reading ability

A previous study of recall of letter strings by good and poor beginning readers IShankweiler, Liberman, Mark, Fowler, & Fischer, 1979 revealed that the performance of good readers was more severely penalized than that of poor readers when the letter names rhymed. To determine whether the differences in susceptibility to phonetic interference extend to materials that more closely resemble actual text, we designed an experiment to test recall of phonetically controlled sentences and word strings. As in the case of letter recall, we found that, although good readers made fewer errors than poor readers when sentences or word strings contained no rhyming words, they did not excel when the materials contained many rhyming words. In contrast to manipulations of phonetic content, systematic manipulations of meaningfulness and variations in syntactic structure did not differentially affect the two reading groups. We conclude that the poor readers’ inferior recall of phonetically nonconfusable sentences, word strings, and letter strings reflects failure to make full use of phonetic coding in working memory.     

Atypical Hemispheric Specialization in Intellectual Deficiency

In order to determine the relation between hemispheric specialization for language and intellectual deficiency, two groups of lower-IQ subjects were compared to normal-IQ controls on word-dichotic listening tasks. Two conditions in which stimuli differed by their level of phonological complexity were used. Normal controls showed the expected right-ear advantage in both conditions. Moreover, they showed a greater magnitude of ear difference on the condition requiring higher-order phonological processing. In the mentally deficient group, almost half the subjects exhibited a left-ear advantage and they showed no difference between the two conditions in terms of the magnitude of ear difference. These results point to the presence of atypical hemispheric specialization in mentally deficient subjects.     

Developmental dyspraxia and developmental coordination disorder

This article discusses the role developmental dyspraxia plays in developmental coordination disorder (DCD), based upon a review of literature on apraxia, developmental dyspraxia, and DCD. Apraxia and dyspraxia have often been equated with DCD. However, it is argued that apraxia and dyspraxia primarily refer to the problems of motor sequencing and selection, which not all children with DCD exhibit. The author proposes to distinguish developmental dyspraxia from DCD. Other issues discussed include the assessment, etiology, and treatment of developmental dyspraxia and DCD, and the relationship between DCD and learning disabilities. A research agenda is offered regarding future directions to overcome current limitation.     

The “Poffenberger” and “Dimond” Paradigms: Interrelated Approaches to the Study of Interhemispheric Dynamics?

Brown and Jeeves (1993) found that an evoked potential estimate of interhemispheric transfer time, from the left to the right hemisphere, correlated negatively with a bilateral field advantage (BFA) in a response-choice letter matching task. We implemented a go no-go dot size matching task to determine whether the crossed-uncrossed difference (CUD) in reaction time, commission errors and omission errors (estimates of the “cost” of interhemispheric transfer) would correlate with BFAs in data from the same experiment and whether the type of decision (“same” versus “different”) would modulate the CUDs and/or BFAs. Sixteen normal right-handed subjects were tested. The CUDs were negatively correlated with the BFAs. Canonical correlation analysis of this set of relations was highly significant (r= .95). Estimates of left-to-right relay were far more strongly related to BFA (p= .0001) than were estimates of right-to-left relay (p= .03). “Same” decisions yielded a unilateral field advantage and “different” decisions a bilateral field advantage in omission error data, this crossed interaction reaching significance. More efficient interhemispheric relay favored BFAs, i.e., strongly suggesting in such cases an advantage of interhemispheric over intrahemispheric integration. This effect appeared to be markedly asymmetric. Furthermore, resource sharing within and between the hemispheres was a function of the “same” versus “different” dimensions of the decision to be made, especially in omission errors. The opposite dissociation occurred less markedly in the reaction times, this double dissociation reaching significance, revealing presence of a subtle speed–accuracy trade-off in interhemispheric dynamics.