Task-hemispheric integrity in dual task performance

A condition of task hemispheric integrity is predicted to result in a dual task situation when the central processing and response components of each task are associated exclusively with a given cerebral hemisphere. The prediction that this condition will generate more efficient time-sharing is tested in a series of four experiments. In experiment 1 the prediction is confirmed when a spatial (tracking) and verbal (letter memory search) task are time-shared, and the hand assignment to task responses is manipulated. In experiment 2 a spatial variant of the memory search is used instead of the verbal letter search, and hand assignment effects are not obtained, since when two spatial tasks are time-shared an integrity assignment is impossible. Experiment 3 validates the hemispheric lateralization of the two single task variants of the memory search task, while experiment 4 establishes the separate “spatial’ and “verbal” resource demands of the two variants by observing their differential interference with concurrent spatial and verbal tasks.     

Structuring decision problems and the ‘bias heuristic’

This paper examines our understanding of the decomposition of immediate acts when structuring decision problems. Seven different types of uncertainties are identified, and four of these are shown to be taken explicitly into account in models within the province of decision theory, described in terms of four interlocking systems interfaced with semantic memory (a core act-event system, and systems buffering utilities, probabilities and events, respectively). Requisite decision modeling is shown to require that the remaining three types of uncertainty (procedural uncertainty; how the decision maker will feel about subsequent acts; agency for changing subsequent states of the world) are also resolved. Methods for ‘fixing’ structure are discussed in terms of aiming at a common understanding about the ‘small world’ in which a decision problem is located. Difficulties in resolving uncertainties in doing this are described. An alternative approach, common in studies invoking ‘behavioural decision theory’ is contrasted: imposing structure, assuming common understanding. The latter approach is shown to involve (i) the ‘naturalisation’ of the small world in which the decision problem is located, and (ii) the utilisation of normative models as ‘ideal types’, leading to the use of the ‘bias’ argument in discussing subjects' performance in decision tasks. Using this argument reflexively, the operation of the ‘bias heuristic’ is identified in a survey of published papers referencing this approach to the study of decision making. Effects identified are: availability of tasks, subjects and explanations; representativeness of findings; and anchoring and adjustment of explanations. Implications for practice are discussed throughout the paper.     

The development of career choices: The relationship between patterns of commitment and career outcomes in adulthood

This study was designed to examine the theoretically predicted adult career outcomes of individuals who engage in different developmental patterns of commitment to choice. It was hypothesized, based on D. E. Super's formulations, that those who engage in increasing commitment and who do not revert to earlier behaviors would experience the most desirable outcomes in adulthood. This hypothesis was tested using an analysis of longitudinal data in relation to career outcomes at two points in adulthood. Minimal support for the hypothesis was found in combination with some findings to suggest that developmental patterns of increasing commitment may not lead to the predicted desirable outcomes. Implications for theory revision and future research are discussed.     

Linguistic recovery after closed head injury

Recovery from acute aphasia after closed head injury was studied in 21 young adults at least 6 months after injury. Three profiles of scores were found using standardized language tests. Persistent expressive and receptive impairment was present in 6 patients who sustained severe diffuse brain injury resulting in global cognitive deficit. Residual expressive impairment, primarily of naming, was associated with mild diffuse brain injury though focal left-hemisphere injury was present in 3 of 6 cases. Patients who recovered to normal levels on all language tests generally had acute neurologic findings consistent with mild diffuse brain injury. Cranial computed tomography at the time of followup frequently disclosed ventricular enlargement.     

Phonological encoding and ideographic reading by the disconnected right hemisphere: Two case studies

The mute disconnected right hemispheres (RHs) of two commissurotomy patients are able to understand spoken words and read printed words by matching them with pictures of the objects named. In this paper we report the results of five experiments. The RH of one patient could “evoke the sound image” of a word to the extent of matching two pictures with homonymous names (experiment 1) or with rhyming names (experiment 2) without being able to name either one. This transformation of picture to covert sound does not depend on orthographic similarity of word ends as a clue to homonymy or rhyme, nor does it improve with short-term learning. Yet neither RH can translate print into sound by matching a spelled word with a picture that has a rhyming name (experiment 3) or by matching two orthographically dissimilar rhymes, be they meaningful (experiment 4) or nonsense words (experiment 5). We suggest that these RHs read “ideographically,” recognizing words directly as visual gestalts without intermediate phonetic recoding or grapheme-to-phoneme translation.     

Control of social desirability in personality inventories: Principal-factor deletion

Rational and statistical techniques for controlling social desirability (SD) in scales derived from self-report inventories are reviewed. The principal-factor deletion technique is explained in detail. It is applied during factor analysis when derived content scales are expected to be tainted with SD. If one principal factor is found to represent social desirability, the implicated factor is dropped and the communalities adjusted before the remaining factors are rotated to a desired simple structure criterion. Subscales derived from resulting factors are free of SD bias. Principal-factor deletion is compared with other approaches including rational techniques, covariate procedures, and target rotation.     

A word-finding computer program with a dynamic lexical-semantic memory for patients with anomia using an intelligent speech prosthesis

A computer program for a portable microprocessor has been developed which aids anomic patients in finding words given clues about the target word. Over time the lexical-semantic memory is reorganized automatically depending on the frequency of word usage by an individual patient. Words can be added or deleted to fit the patient's idiosyncratic lexicon. A clinical example is given. The program is being tested with a variety of aphasic-anomic patients with major word-finding difficulties.     

Lateralization of temporal lobe dysfunction and verbal encoding

The contribution of encoding deficits to verbal-learning difficulties known to be associated with temporal lobe dysfunction was investigated. Auditory and visual false-recognition tasks, which assess verbal encoding strategies, were given to patients with left-temporal-lobe (LTL) and right-temporal-lobe (RTL) surgical excisions and to a group of normal controls (NC). On both auditory and visual tasks, LTL patients made significantly more false-recognition errors than the other subjects on related, but not unrelated, words in the test list. The findings indicate that LTL patients are able to initially encode verbal material and that a breakdown in information processing occurs at a later stage. On the auditory tasks, the performance of RTL patients did not differ from that of NC subjects. However, on the visual tasks, RTL patients, as compared to both LTL and NC subjects, made fewer false-recognition errors. The performance of RTL patients, in contrast to LTL patients, could be interpreted as a reduced encoding of the visual attribute of verbal material. Another possible explanation considered was difficulty in familiarity discrimination.     

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.     

Vocal and nonvocal discriminative performance in monkeys

Discriminative performance of a lever press and a vocal call was compared in five macaques. The animals exhibited similar scores for Response Rate, Efficiency, and Error Index. Total vocal responses were slightly higher than total lever responses. Latency for vocal responses was significantly greater than lever press. Similar scores in measures of performance of the two behaviors indicate that discriminative vocalization is not exceedingly difficult. Failure by others to achieve discriminative vocalization in studies employing weak positive-reinforcement contingencies suggest that certain experimental paradigms are unsatisfactory for vocal conditioning.