Semantic feature representations for normal and aphasic language

Aphasic and non-neurological patients grouped nouns on the basis of similarity of meaning. These word groupings served as input matrices for hierarchical clustering and multidimensional scaling analyses. The emergent structures suggest that, while the normal adult has a number of levels upon which to organize his lexicon, the adult aphasic's lexicon can be characterized as a set of partial entries that are tied to affective and situational data. The results also suggest that semantic feature representations derived from similarity-of-meaning judgments are of relevance in the study of factors which influence actual language performance.     

Moral reasoning development and graduate education

The Defining Issues Test (DIT) of moral reasoning development was administered to 20 advanced and 20 first-year graduate students, plus 40 college graduates matched to the graduate groups on sex, age, and verbal ability. A two-way ANOVA design was used to infer whether graduate education, selection, maturation, or a combination of these effects is (are) associated with group differences on the DIT. Results suggest that differences found between the graduate students and college graduates can be accounted for by a combination of maturational and selection effects, contrary to the hypothesized effects of formal education.     

Reaction time, intelligence, and attention

The roles of attention in reaction time and in the relationships among reaction time, intelligence, and achievement were analyzed. The subjects were 105 seventh-grade children. The results were generally consistent with most studies involving the Hick paradigm: both mean reaction time and the standard deviation of reaction time correlated with the intelligence and achievement measures used. Reaction time measures were correlated with attention and perceptual speed as well as with general intelligence, or g. Implications of these results for current theories linking reaction time and intelligence are discussed.     

Intratrial proactive interference in pigeon short-term memory: Manipulation of stimulus dimension and dimensional similarity

Proactive interference was studied using an intratrial preparation in two delayed matching-to-sample experiments employing pigeons. On interference trials, an interfering sample and a target sample were presented successively and were followed by a test consisting of a choice between two stimuli, one associated with each sample. Control trials were identical to interference trials except that the interfering sample was not presented. On both types of trials, choice of the comparison corresponding to the target sample was defined as correct. Colored fields and line orientations were employed as sample stimuli in Experiment 1, and samples of food and no food and of number of pecks were employed in Experiment 2. Interference was found to be equally robust regardless of whether the interfering and target samples were each selected from any of the four dimensions (color, line orientation, food/no food, or number of pecks). Amount of interference was found to be independent of whether the interfering and target samples employed on a trial were selected from the same dimension or from different dimensions. Evidence was also obtained suggesting that line orientation comparison stimuli are more likely to elicit a response not based on memory than are color comparison stimuli.     

The infant's acquisition of knowledge of bimodally specified events

Four-month-old infants viewed, for a duration of several minutes, two objects that bounced in synchrony with two percussion sounds. This synchrony was the only information tying each sound to its respective object. During the viewing the infants learned about the relationships between sound and object. Learning was revealed in two ways. In a search test, infants looked for an object when its sound was played. In a transfer test, infants' declining interest in a sound presented alone generalized to the visible object that the sound specified. Studies that reversed the spatial locations of the objects revealed that sound-object learning, rather than place or response learning, guided infants' perceptual exploration.     

Effect of mutual acquaintance on the construction of conversation

In a previous investigation, we demonstrated the role of questions as an instructional resource in the social construction of conversation by depriving conversationalists of their use. The resulting conversational structure, measured in terms of the ability of third parties to reconstruct the dialogues after they had been randomized, was impaired. The importance of culturally shared knowledge for the reconstruction (and by implication the construction) task was apparent in the superiority of British over Canadian subjects in reconstructing unconstrained British dialogues. The present study was concerned with the effects of privately shared knowledge on the construction of conversation. Conversational structure and the frequency of questions were greater in strangers' than in mutual acquaintances' unconstrained dialogues. Strangers' dialogues, but not those of mutual acquaintances, were disrupted under a ban on questions. The results were taken to indicate that strangers need to provide one another with continual instruction in how to proceed, whereas mutual acquaintances, in virtue of their privately shared social knowledge, can construct orderly dialogue with less moment-to-moment guidance.     

Sequential item selection: Optimal and heuristic policies

This paper considers testing in which the goal is to minimize the number of test items required to establish a learner's state of ability. Focus is on optimal or near optimal selection over a well-defined universe of items or stimuli. Selection policies are determined for the case in which the items have hierarchical or partial hierarchical relationships. Derivation of an optimal policy rests upon techniques from dynamic programming. For situations in which an optimal policy may be too costly to compute, two heuristic approximations are offered. One heuristic counts the hypothetical estimates of ability that remain tenable following a response to each item and chooses the item that minimizes the expectation of that number. The other selects the item that maximizes the statistic of information.     

Disfluent speech associated with brain damage

The frequency and type of disfluencies in the spontaneous speech of 15 people with Broca's aphasia and right hemiplegia was studied. Two aged-matched control groups (15 nonaphasic stroke patients with left hemiplegia and 15 normals) were also studied. The frequency of disfluencies in the speech of aphasics was three times greater than that in the speech of either control group. However, most of the disfluencies uttered by aphasics were of the types commonly found in speech of normals.