Sex differences in cognitive abilities: a cross-cultural perspective.

Studies in Western cultures have indicated significant sex differences in certain cognitive abilities. To determine whether similar differences occur in a non-Western culture, this study administered a cross-linguistic battery of tests to high school students in Japan and America. In both cultures, girls averaged significantly higher scores on a Story Recall test, the Digit-Symbol test and a Word Fluency test whereas boys achieved significantly higher scores on a Mental Rotation test. The analysis of standardized test scores further indicated that the size of the sex difference was culture-independent in three out of these four cases. These results are discussed in the context of the GESCHWIND and GALABURDA [Cerebral Lateralization, Biological Mechanisms, Associations and Pathology, Bradford Books, Cambridge, Massachusetts] account of the contribution of testosterone to left-right asymmetries in early cerebral development.

Different loci suggested to mediate tilt and spiral motion aftereffects.

Interocular transfer of two figural aftereffects was examined in orthotropes and strabismic subjects. Within both groups there were persons with an appreciable degree of stereoacuity and others who had little or none. Experimental evidence from a variety of sources has suggested that stereopsis depends upon binocularity of units in the geniculostriate system. For the tilt aftereffect, interocular transfer correlated with stereoacuity among both orthotropes and strabismics. For the spiral motion aftereffect, interocular transfer did not correlate with stereoacuity; it was present among orthotropes and absent among strabismic individuals. The correlation of stereoacuity with interocular transfer of the tilt aftereffect agrees with previous observations and is consistent with the interpreation that this effect is mediated at a cortical level. The lack of a correlation between stereoacuity and interocular transfer of the spiral motion aftereffect suggests that this effect is mediated by units other than those responsible for stereopsis. Richards and Smith, on the basis of certain phenomenal differences between the spiral motion aftereffect and other figural aftereffects, have suggested that the former is mediated at a midbrain level. If strabismic persons lack binocular units in midbrain, the present results are consistent with their hypothesis.

Using children's humor to clarify the relationship between linguistic awareness and early reading ability.

This study uses linguistic humor to show that an awareness of only those linguistic units transcribed by the orthography bears a special relation to early reading success. The subjects were 48 second-grade children tested on ten "phoneme/morpheme" riddles which manipulate phonemes and bound morphemes and ten "control" riddles which depend on awareness of other aspects of linguistic structure and "common sense". Each child also received the Word Identification and Word Attack subtests of the Woodcock Reading Mastery Tests and the Peabody Picture Vocabulary Test. Reading ability was significantly related to correct resolution of the phoneme/morpheme riddles but not to correct resolution of the control riddles. PPVT scores were significantly related to performance on both types of riddles but not to reading ability. Thus, while IQ is related to the resolution of riddles in general, reading ability has a special relation to riddles which manipulate phonemes and morphemes, consistent with the morphophonological nature of English orthography.

Right hemisphere specialization for mental rotation in normals and brain damaged subjects.

Hemisphere specialization for mental rotation was investigated utilizing Shepard's (1971) paradigm. In each of two experiments, the procedure involved presenting pairs of novel non-verbal stimuli at various angles of disparity. Subjects were instructed to construct a mental image of one stimulus, rotate this image, and judge whether or not the image was a congruent match with its mate. Both response time and accuracy were measured. In Experiment 1, the testing of right-handed normals revealed a significant left visual field advantage for accuracy (p less than .0001) and response time (p less than .05). In Experiment 2, a comparison of right parietal lesioned patients with both left parietal lesioned patients and matched normal controls likewise revealed significant right lesion effects for accuracy (p greater than .0001) and response time (p greater than .01). Right hemisphere specialization for mental rotation was documented for both normals and brain damaged subjects.

Spoken sentence comprehension by good and poor readers: a study with the Token Test.

Good and poor readers in the third grade (age nine years) were examined on a test of immediate memory for word strings and on a version of the Token Test (De Renzi and Faglioni, 1978) to assess sentence comprehension. The poor readers made more errors than the good readers in recall of word strings and on some Token Test items. Those Token Test items that impose the greatest burden on short-term memory were the most sensitive to reader group differences; syntactic complexity alone did not distinguish the groups. The findings support other indications that poor readers make less effective use of working memory in processing spoken sentences than good readers; they do not indicate a syntactic deficit on the part of the poor readers.

Children's memory for recurring linguistic and nonlinguistic material in relation to reading ability.

Good beginning readers typically surpass poor beginning readers in memory for linguistic material such as syllables, words, and sentences. Here we present evidence that this interaction between reading ability and memory performance does not extend to memory for nonlinguistic material like faces and nonsense designs. Using an adaptation of the continuous recognition memory paradigm of Kimura (1963) we assessed the ability of good and poor readers in the second grade to remember three different types of material: photographs of unfamiliar faces, nonsense designs, and printed nonsense syllables. For both faces and designs, the performance of the two reading groups was comparable; only when remembering the nonsense syllables did the good readers perform at a significantly superior level. These results support other evidence that distinctions between good and poor beginning readers do not turn on memory, per se, but rather on memory for linguistic material. Thus they extend our previous finding that poor readers encounter specific difficulty with the use of linguistic coding in short-term memory.

Contrast effects do not underlie effects of preceding liquids on stop-consonant identification by humans.

These experiments explored the claim by A. Lotto and K. Kluender (1998) that frequency contrast explains listeners' compensations for coarticulation in the case of liquid consonants coarticulating with following stops. Evidence of frequency contrast in experiments that tested for it directly was not found, but Lotto and Kluender's finding that high- and low-frequency precursor tones can produce contrastive effects on stop-consonant judgments were replicated. The effect depends on the amplitude relation of the tones to the third formant (F3) of the stops. This implies that the tones mask F3 information in the stop consonants. It is unknown whether liquids and following stops in natural speech are in an appropriate intensity relation for masking of the stop. A final experiment, exploiting the McGurk effect, showed compensation for coarticulation by listeners when neither frequency contrast nor masking can be the source of the compensations.

Longitudinal prediction and prevention of early reading difficulty.

The results of many studies suggest that early reading problems are associated with deficiencies in certain spoken language skills. Children who encounter reading difficulty tend to be deficient in the perception of spoken words, the ability to retain linguistic material in temporary memory, and the ability to comprehend certain spoken sentences, as well as in their awareness about the phonological structure of spoken words. This paper summarizes these findings and provides an explanation in terms of the requirements of skilled reading. It further reviews the results of two longitudinal studies which show that inferior performance in kindergarten tests of language skills may presage future reading problems in the first grade. Based on these studies, procedures are suggested for kindergarten screening and for some ways of aiding children who, by virtue of inferior performance on the screening tests, might be considered at risk for early reading difficulties.

Repetition and comprehension of spoken sentences by reading-disabled children.

The language problems of reading-disabled elementary school children are not confined to written language alone. These children often exhibit problems of ordered recall of verbal materials that are equally severe whether the materials are presented in printed or in spoken form. Sentences that pose problems of pronoun reference might be expected to place a special burden on short-term memory because close grammatical relationships obtain between words that are distant from one another. With this logic in mind, third-grade children with specific reading disability and classmates matched for age and IQ were tested on five sentence types, each of which poses a problem in assigning pronoun reference. On one occasion the children were tested for comprehension of the sentences by a forced-choice picture verification task. On a later occasion they received the same sentences as a repetition test. Good and poor readers differed significantly in immediate recall of the reflexive sentences, but not in comprehension of them as assessed by picture choice. It was suggested that the pictures provided cues which lightened the memory load, a possibility that could explain why the poor readers were not demonstrably inferior in comprehension of the sentences even though they made significantly more errors than the good readers in recalling them.

Phoneme awareness and future reading ability.

This study investigates two group-administered tests of phoneme awareness, a phoneme segmentation test and an invented spelling test. Each was given to 100 kindergarten children (48 female, 52 male), along with two tests of visual-motor ability. One year later the same children received standardized reading tests and portions of an IQ test. Scores on each test of phoneme awareness predicted between 30% and 40% of variance in first-grade reading ability. In contrast, scores on the tests of visual-motor ability bore a less systematic, less substantial relation to future reading ability.

Phonological processing, language comprehension, and reading ability.

Previous research has indicated a relationship between reading ability and the integrity of certain phonological processing skills--skills that operate on the sound structure of language. This study shows how the deficient phonological processing skills of poor beginning readers can impair their comprehension of spoken phrases and sentences that are disambiguated by prosodic cues (i.e., pitch, stress, and pause). Following a brief summary of the available research literature, two new experiments are reported to illustrate that poor readers do not interpret certain sentences as accurately as good readers do, because they are less able to hold phonological material temporarily in working memory. Further insight into the basis of these differences between good and poor readers is provided by two additional pieces of evidence: The differences between good and poor readers are analogous to those between older and younger children readers, and the performance of poor readers tends to resemble that of younger children reading at their same level (i.e., reading-ability-matched controls). Apparently, good and poor readers tend to differ in the rate at which they develop phonological processing skills.

Fricative-stop coarticulation: acoustic and perceptual evidence.

Eight native speakers of American English each produced ten tokens of all possible CV, FCV, and VFCV utterances with V = [a] or [u], F = [s] or [integral of], and C = [t] or [k]. Acoustic analysis showed that the formant transition onsets following the stop consonant release were systematically influenced by the preceding fricative, although there were large individual differences. In particular, F3 and F4 tended to be higher following [s] than following [integral of]. The coarticulatory effects were equally large in FCV (e.g.,/sta/) and VFCV (e.g.,/asda/) utterances; that is, they were not reduced when a syllable boundary intervened between fricative and stop. In a parallel perceptual study, the CV portions of these utterances (with release bursts removed to provoke errors) were presented to listeners for identification of the stop consonant. The pattern of place-of-articulation confusions, too, revealed coarticulatory effects due to the excised fricative context.

Perceptual assessment of fricative--stop coarticulation.

The perceptual dependence of stop consonants on preceding fricatives [Mann and Repp, J. Acoust. Soc. Am. 69, 548--558 (1981)] was further investigated in two experiments employing both natural and synthetic speech. These experiments consistently replicated our original finding that listeners, report velar stops following [s]. In addition, our data confirmed earlier reports that natural fricative noises (excerpted from utterances of [st alpha], [sk alpha], [(formula: see text)k alpha]) contain cues to the following stop consonants; this was revealed in subjects' identifications of stops from isolated fricative noises and from stimuli consisting of these noises followed by synthetic CV portions drawn from a [t alpha]--[k alpha] continuum. However, these cues in the noise portion could not account for the contextual effect of fricative identity ([formula: see text] versus [sp) on stop perception (more "k" responses following [s]). Rather, this effect seems to be related to a coarticulatory influence of a preceding fricative on stop production; Subjects' responses to excised natural CV portions (with bursts and aspiration removed) were biased towards a relatively more forward place of stop articulation when the CVs had originally been preceded by [s]; and the identification of a preceding ambiguous fricative was biased in the direction of the original fricative context in which a given CV portion had been produced. These findings support an articulatory explanation for the effect of preceding fricatives on stop consonant perception.

Influence of preceding fricative on stop consonant perception.

The effect of a preceding fricative on the perceived place of stop consonant articulation was investigated in a series of experiments. In experiment 1, we preceded synthetic syllables from two [tV]--[kV] continua with fricative noises appropriate to [integral of] or [s] and showed that more velar stops are perceived in the context of [s]. Experiment 1 also demonstrated a decrease in the magnitude of this perceptual context effect with increased temporal separation of fricative noise and CV portion, and with introduction of a vowel before the noise, which permitted a subjective syllable boundary after the fricative. Experiment 2 showed that although the effect of the fricative on stop perception declines initially with temporal separation, it may persist in reduced form over intervals as long as 375 ms. Experiment 3 replicated the basic fricative context effect using improved stimuli, but failed to replicate the reduction with an intervening syllable boundary obtained in experiment 1, which presumably was due to the vowel preceding the fricative. Experiments 4 and 5 revealed that the fricative context effect depends both on the phonetic category assigned to the fricative and on the specific spectral properties of the fricative noise. Experiment 5 also revealed a reciprocal effect of the stop consonant on fricative identification. We hypothesize that these perceptual effects serve to compensate for coarticulatory dependencies between stop consonants and preceding fricatives.