Variations in patterns of lateral asymmetry among dextrals

Evidence supporting individual variations in patterns of hemispheric involvement in the recognition of visuo-spatial and verbal stimuli among dextrals is reported. In Experiment 1, subjects' asymmetry scores on a task that was nonlateralized for the group as a whole were significantly correlated with their asymmetry scores on right-hemisphere-specialized tasks, including face recognition. In Experiment 2, subjects' asymmetry scores on a task that was nonlateralized for the group as a whole were significantly correlated with their asymmetry scores on a left-hemisphere-specialized word recognition task. These results suggest that individual dextrals' asymmetry scores on lateralized tasks are a joint function of a subject's underlying hemispheric specialization for that task and stable individual variations in asymmetric hemispheric reliance.     

Right hemisphere superiority in the recognition of famous faces

Words and famous faces were tachistoscopically presented in bilateral view to normal right-handed subjects. A left visual field advantage was obtained for famous faces whether naming or recognition from an array was required and a right visual field advantage was obtained for words. While the finding of a left visual field advantage for the recognition of famous faces is consistent with studies of face recognition deficits in brain-damaged patients, a right visual field advantage for the recognition of famous faces has recently been reported in normal subjects. Possible explanations for this discrepancy are discussed.     

Lateral asymmetries in the naming of words and corresponding line drawings

Laterally displaced line drawings and the words which name these drawings were tachistoscopically presented to adult subjects. For words, as expected, a right visual field-left hemisphere advantage was obtained. For line drawings, in contrast to previous studies which have typically reported a right visual field-left hemisphere advantage, no visual field asymmetry was found. The absence of a visual field asymmetry for line drawings is consistent with reports of a shift toward greater right hemisphere involvement in the recognition of pictographic as compared to phonetic writing systems and concrete/imageable words as compared to abstract/nonimageable words. Further, the present results seem consistent with findings on picture recognition and naming abilities in brain-damaged patients.     

Developmental changes in face processing: results from multidimensional scaling

Multidimensional scaling procedures were used to investigate developmental changes in the ability to process previously unfamiliar faces. Eighty male subjects, aged 7, 9, 12, or adult, rated the similarity of pairs of faces. The faces were presented to subjects in either the upright or the inverted orientation. Multidimensional scaling analyses suggest that subjects of all ages use similar information in judging the similarity of faces. However, for upright faces, individual subjects under age 10 seem to use fewer features at a time. The results argue against a qualitative shift in face processing at age 10, and suggest that the improvement in face recognition ability noted at this age is due at least in part to an increased ability to consider more features simultaneously.     

A review, analysis, and some new data on hand-posture distributions in left-handers

Different methods have been employed to assess handwriting posture in left-handers, and different dimensions of hand posture have been used for categorization. Within North American samples, there is a remarkable consistency between studies in the distributions when the same assessment method is used, but there are very large and highly significant differences for different methods of assessment. The various methods and dimensions of categorization evidently index different variables, and these are likely to have different relations with neuropsychological factors. It is possible, however, to gather questionnaire data on handwriting posture that closely resemble direct experimenter observation, as a brief report on left-handed males shows.     

Statistical significance tests for binormal ROC curves

Statistical significance tests are derived and evaluated for measuring apparent differences between an obtained and an expected binormal ROC curve, between two independent binormal ROC curves, and among groups of independent binormal ROC curves. A binormal ROC curve is described by two parameters which represent the spread of the means and the ratio of the standard deviations of the two underlying Gaussian decision variable distributions. To test the significance of apparent differences between or among ROC curves, approximate χ² statistics for each of the three tests were constructed from maximum likelihood estimates of the two parameters defining the binormal ROC curve. The performance of each test statistic was evaluated by simulating five-category rating scale data with equal numbers of noise and signal-plus-noise trials (set at 50, 250, and 500) for each of three typical ROC curves. For the significance test involving only one ROC curve, rating scale data were generated from the chance diagonal of the ROC space also. Although test performance was found to be somewhat dependent on the number of trials and on the location of the ROC curve in the ROC space, comparisons of the obtained and expected fractions of (falsely) significant results at various α levels showed the proposed statistical significance tests to be reliable under practical experimental conditions.     

Children's decision strategies and their adaptation to task characteristics

Recent research has established decision making as an important type of strategic problem solving. From this perspective, the present paper examines strategic decision behavior in children and, in particular, the ability to adapt decision strategies to task characteristics. Twelve-year-olds' strategies were identified through analyses of information search patterns with different-sized matrices of information. Using a similar procedure, Payne (1976, Organizational Behavior and Human Performance, 16, 366–387) found that adults shifted to more efficient (but less “optimal”) strategies as task complexity increased. The present study indicates that, by 12 years of age, children understand many of the basic concepts of strategic decision making, such as compensation and elimination, and, like adults, they modify their strategies appropriately in response to complexity. However, their behavior differs from that reported for adults in that the distinctions among specific decision strategies are not clear cut, and there is frequent use of less demanding, cost-cutting strategies even with smaller decision tasks. Memory capacity and topic interest also affect decision strategy. The results support the feasibility of further developmental study of decision strategies. Analytical techniques developed here for use with children may profitably be applied in studies with adults as well.     

The suppression of crying in the human neonate: response to human vocal tract stimuli

Amounts of crying were measured for two groups of infants in two states, calm and crying. The stimulus group was exposed to two test-cry stimuli (own-cry/other-cry) in both states. The control group was not exposed to the test-cry stimuli. For the stimulus group, results showed that there was no significant difference in the amount of crying during presentation of either the own-cry or other-cry test stimulus. However, the stimulus group did cry significantly less than the control group. This difference in the amount of crying was attributed to the capacity of the infant to suppress crying in the presence of auditory stimuli.     

Consistency and modification of judgment

In an investigation of minority influence, it was predicted that a consistent preference for paintings based on nationality by a confederate would cause previously neutral subjects to increase their preference in the direction of this minority viewpoint. Further, it was predicted that ethnic origin of the confederate could be seen as a biasing factor which could diminish influence. Four naive subjects were paired with one experimental confederate who was presented as being of either Italian, German, or unknown ethnic origin. On every trial, subjects were asked to indicate their preference between two paintings, one labeled “Italian” and the other labeled “German.” Labels were actually assigned at random. The confederate consistently chose the Italian or the German paintings on every one of the 19 trials. Results indicate that Control subjects rather than being neutral, exhibited a preference for the Italian paintings. Further, the presence of a confederate who took a consistent standard, whether it was Italian or German, had the effect of making subjects significantly more pro-German (or less pro-Italian) than the control group. The findings are explained on the basis that the German position was actalternative minority position, whereas the Italian position was actually an extreme of the majority position. While the former situation leads to minority influence as predicted, the latter situation appears to have polarized subjects. An alternative in terms of a norm of fairness is suggested, also.     

Hemifield independence in the left handed

Tachistoscopically presented arrays containing either a single word or two words in different configurations were given to left- and right-handed subjects. Several measures indicated hemifield, and by implication, hemispheric independence for word recognition was more likely to be found among left- than right-handers. Differences within the left-handed group associated with the presence of family sinistrality and writing posture were also found. Results were discussed with respect to the view that bilateral representation of language frequently occurs in left-handed adults.     

Semantic priming effects for stimuli presented to the right and left visual fields

Studies that have addressed the possibility of hemispheric differences in semantic priming effects have yielded contradictory results. This paper reports the findings of two experiments intended to shed greater light on the issue of hemispheric differences in semantic priming. Experiment 1 used a hemiretinal paradigm and examined manual response latency and response accuracy to four types of word pairs; categorically related, syntactically related, unrelated, and pairs containing a nonword member. Experiment 2 examined the effects of unrecognized, disambiguating flank words on verbal responses to a centrally presented homograph. Experiment 1 yielded no significant visual field differences in magnitude of priming effects when response latency served as the dependent measure, although categorical relatedness facilitated response accuracy for left but not right visual field stimuli. In experiment 2, the disambiguating words had a significant effect on meaning interpretation of the homographs that was independent of visual field of presentation. Taken together, the results of these studies are interpreted as indicating that semantic aspects of linguistic input are automatically processed and can influence the content and latency of subsequent responses, whether presented to the left or right visual field.     

Hand inversion in sinistrals and lateral preference: Comments on Searleman, Porac, and Coren (1984)

A reanalysis of data from left-handers presented by A. Searleman, C. Porac, and S. Coren, (1984, Brain and Cognition, 3, 86–93) cautions against premature conclusions that an inverted handwriting posture is more prevalent for sinistral men with leftward lateral preferences and for women with rightward or mixed lateral preferences. Although this may eventually prove to be true, the findings of Searleman et al. (1984) are insufficient for supporting this inference.     

Probe similarity and recognition of set membership: A parallel-processing serial-feature-matching model

A model for memory scanning is proposed in which the encoded representation of a probe is compared in parallel with encoded representations of each item in the positive set. The within item matches are serial feature by feature comparisons that terminate when either a positive or negative criterion is reached. This model is shown to predict the results of a probe similarity experiment. The serial location of a similarity within an item affects negative reaction times, but the number of items in the positive set to which the probe is similar has no main effect. The model is also shown to yield predictions consonant with existing data on the relation between reaction times and set size and speed-accuracy trade offs.     

On signalling that it's your turn to speak

The operation of a “speaker-state signal” in two-person, face-to-face conversations is hypothesized. Display of this signal by an auditor appears to indicate, among other things, that he is claiming the speaking turn, differentiating this action from a “back-channel behavior” by which he merely acknowledges some portion of the speaker's message. The signal also appears to play a part in the resolution of situations in which both participants simultaneously claim the speaking turn. The signal is defined as the display of at least one of a set of four behavioral cues, two in paralanguage and two in body motion.     

Possible psychometric problems in a test for selective deficits of conceptualization

We administered a modified version of the test of Semenza, Denes, Lucchese, and Bisiacchi (Brain and Language, 10, 243-248 (1980)) for selective deficits in conceptualization to a group of normals and psychiatric patients. Analysis of the results obtained with the normal sample revealed several psychometric problems. The two components of the test (one for thematic and one for class relationships) each had poor internal consistency and were significantly different from each other on a measure of discriminating power. It is not clear if our results are related to difficulty in applying the test to an English-speaking population or reflect inherent psychometric problems.     

Effects of eye movements on the recognition and localization of dichotic stimuli

Three experiments examined the effect of gaze shifts on overall performance and ear differences in dichotic listening. In the first two experiments, lights were switched on and off so as to induce rightward, leftward, or upward gaze during dichotic stimulation. The dichotic material consisted of musical passages in Experiment 1 and two kinds of verbal material in Experiment 2. Vertical eye movements enhanced the accuracy of identification of music but not verbal material. The lateral direction of eye movements affected subjects' ability to localize targets in Experiment 1: localization was more accurate in the direction toward which subjects were looking. In the third experiment it was found that optokinetic nystagmus (OKN) influenced the asymmetry of performance on a dichotic consonant-vowel (CV) test. The right-ear advantage was greatest when the OKN drum rotated from left to right and least when it rotated from right to left. The effect was due to corresponding variation in left-ear scores. Possible mechanisms through which shifts of gaze affect auditory identification and localization are proposed.     

The right hemisphere and temporal processing of consonant transition durations: electrophysiological correlates

Auditory evoked responses (AER) were recorded from frontal, temporal, and parietal scalp regions to a series of consonant-vowel syllables which varied in the duration of the consonant transition. Multivariate analyses of the AER waveforms identified one component of the AERs occurring only over right hemisphere regions which discriminated between differences in transition durations. A second component detected over only left hemisphere areas discriminated differences in place of articulation. These data are consistent with previous behavioral and electrophysiological reports that the right hemisphere is sensitive to temporal discriminations.     

Familiarity decisions for faces presented to the left and right cerebral hemispheres

Right-handed subjects were asked to decide whether or not faces presented briefly in the RVF or in the LVF were familiar (familiar faces were those of famous people). This task avoids the need for extensive semantic processing or temporary storage involved in conventional naming or identification tasks, and thus eliminates the contribution of such factors to any observed asymmetry. The resulting finding of faster reaction times to LVF faces, with no overall visual hemifield difference in error rates, is taken to indicate a right-hemisphere superiority either in the processes used to construct facial representations or in the accessing of face recognition units, or both.     

Quantification and semantic memory

Two models are considered for how people verify explicitly quantified sentences, such as All fathers are parents and Some fathers are parents. The models share the same second stage, but have different first-stage mechanisms. In the Predicate Intersection Model, suggested by Meyer (1970), the first stage involves a serial, self-terminating search among names of categories that intersect the predicate category. In the Feature Comparison Model (Smith, Shoben & Rips, 1974a), the first stage involves evaluating the overall relatedness between the subject and predicate categories by comparing their semantic features. To test the models, three reaction time experiments required subjects to verify statements quantified by Some or All. In the first experiment, the semantic relatedness of categories in false Some-statements was varied. Contrary to predictions of the Predicate Intersection Model, related categories increased reaction time for both true and false Some-statements. While the first experiment revealed that All-statements took longer to verify than comparable Some-statements, the second experiment demonstrated that the All-Some difference can be eliminated by presenting both statement types in the same block of trials, also disconfirming the Predicate Intersection Model. Finally, Experiment III examined the meaning of Some-statements in more detail by having subjects interpret the quantifier Some as “some but not all.” With this interpretation, Some-statements took longer to verify than All-statements. Overall the results support the Feature Comparison Model.