The integrative action of the cerebral hemispheres

In four experiments, right-handed subjects were asked to identify uppercase letters presented tachistoscopically in the right (R) or left (L) visual field or in both visual fields simultaneously (RL). When R, L, and RL trials were randomized together and RL trials consisted of the same letter in each visual field (Experiments 1 and 2), 11 of 21 male subjects (Experiment 1) and 9 of 18 female subjects (Experiment 2) showed a strong left-visual-field advantage, and the remainder in each experiment showed an equivalently strong right-visual-field advantage. When the RL trials consisted of a different letter in the two visual fields (Experiment 3), a consistent right-visual-field advantage was observed. It is argued that these results reflect predominantly analytical (left-hemisphere) processing of “different” pairs and relatively holistic processing of “same” pairs, which induces a shift toward a right-hemisphere advantage in some subjects. The main purpose of three of the four experiments was to test five probability models of hemispheric integration: (1) statistical summation, which assumes that the hemispheres operate independently; (2) redundancy, which assumes that RL decisions reflect only processing by the more specialized hemisphere; (3) complete dependency, according to which RL decisions are the mean of Rand L decisions; (4) integration, which assumes that R and L decisions can be represented as vectors in a joint RL space; (5) correlation, according to which the Rand L decisions are assumed to be statistically dependent. Whether R, L, and RL trials were randomized together or RL trials were presented in separate blocks, models 1 and 4 could be clearly rejected. In general, the best predictor of RL performance was model 5. It is argued that the hemispheres function as an integrated system in letter identification.     

A computer-oriented task analysis method for mathematics instruction

Components of a computer solution for fraction problems in arithmetic have an analog in a new approach to educational task analysis. The components may be called goal-setting or planning elements, in contrast to the goal-satisfying or behavioral steps emphasized in much contemporary task analysis. A hypothetical tutorial dialogue in which a student is asked to tell a tutor what step to perform next is presented as an example of the emphasis of the planning side of computation. Explicit identification of goal-setting elements of a task is illustrated by analysis of the task of converting a pair of fractions to a new pair with a common denominator. The decomposition thus produces is simulated with two computer programs: (1) a LISP program using a set of production rules consisting of conditions to be met and subsequent actions to be taken and (2) a PROLOG program stating goals and solving goals explicitly.     

Selected linguistic and perceptual abilities of empirically derived subgroups of learning disabled readers

A battery of eight linguistic and perceptual tests chosen because of their use in previous research and in the public schools was administered to 100 school-verified verified learning disabled readers (LDR) and 50 normal readers (NR) matched for age and IQ. Standard scores, derived from a comparison of each LDR child's score with the NR group's performance on each diagnostic measure, were cluster analyzed to identify subgroups within the LDR group. Six LDR subgroups were found. Multivariate analysis of variance and discriminant analysis indicated that all LDR subgroups were significantly different from one another as well as significantly different from the NR group's performance on the diagnostic battery. In addition, significant differences were found among the six LDR subgroups on measures of oral reading, reading comprehension, and spelling skills. However, the six groups did not differ with respect to family history variables and the attainment of developmental milestones. These results were compared with those of previous studies and were examined for their implications for a more precise match between LDR learner characteristics and type of teaching method and/or materials.     

Implications of two local consistency strategy selection models

This paper examines some mathematical implications of two process models of concept identification, the 1-element strategy selection model with a local consistency assumption and Chumbley's hypothesis manipulation (HM) model. Under slightly restrictive assumptions, each process model (Level 1) is shown to imply a stochastic model (Level 3), making predictions of behavior in experimental situations in which the stimulus presented to a subject on any trial is randomly selected and independent of that presented on any other trial. In addition, each model is shown to make predictions at an intermediate level (Level 2) about performance on successive trials with specific stimulus sequences presented.At Level 2, each model is shown to falsely predict zero probabilities for particular response patterns when stated stimulus sequences are used. Fewer such problems arise with the HM model than with the 1-element model. Minimum squared error fits of one set of experimental data show relatively good correspondence of predictions and observations when a Chumbley model with different saliences for different hypotheses is employed.     

Distance discrimination in a simulated space environment

The just noticeable difference (JND) for distance was investigated by a paired-comparisons method using successive comparisons. The research utilized an optically simulated large target located in a textureless environment at distances along the saggital plane out to 12, 800 ft. The value of ΔD/D varied from less than 3% at 200 ft to about 7% at 12, 800 ft. The results confirmed a power function relationship between distance threshold and observation distance.     

The effect of foregrounding on readers’ use of predictive inferences

This research extends previous attempts to determine whether subjects make predictive inferences during comprehension. For example, when subjects read a passage about someone falling out of a 14th-story window, do they infer that the person is dead? Previous research in which lexical decision, word naming, and recognition tasks have been used for detecting predictive inferences has had mixed results. In experiment 1, a word-stem completion task was used to test for predictive inferences. The word stems were formed from target inferences that followed either priming or control passages. The data revealed that predictive inferences are generated only about concepts that are foregrounded in the passages. In Experiments 2 and 3, lexical decision and naming were used to test for predictive inferences. The lexical decision data replicated the word-stem completion data. A control experiment ruled out a simple context-checking explanation for the lexical decision results. The naming data indicated that this tasks was not sensitive to elaborative inference generation. Theresults show that readers make predictive inferences, but do so selectively.     

Delusional verbalizations and beliefs

This study evaluated the intensity of delusional beliefs during the modification of delusional verbalizations with three chronically mentally ill inpatients. The multiple-baseline across responses design was used to evaluate the efficacy of a behavioral treatment package to modify delusional verbalizations. Results revealed that changes were obtained in delusional verbalizations to personal questions without corresponding changes in the subjects' delusional beliefs. Changes in delusional verbalizations were well-maintained for two subjects during a 6-month follow-up period. Mixed results were obtained for generalization probe interviews.     

Influence of a Photograph on a Charitable Appeal: A Picture May Be Worth a Thousand Words When It Has to Speak for Itself

Several studies were conducted examining the influence of the use of photographs of a needy individual on a charity appeal for either a well-known or lesser-known charity organization. Results of an initial study indicated that people expected the use of a photograph to enhance the effectiveness of a door-to-door solicitation campaign and that a well-known charity would fare better than a lesser-known one in its efforts. Results of two subsequent studies involving door-to-door solicitations, however. indicated that the proportion of people contributing and the average amount contributed was not dependent upon either the photograph or familiarity with the charity. A final study using a passive countertop solicitation in stores did result in greater contributions when the photograph was present, whereas there was no difference due to charity familiarity. These findings are discussed in terms of image-maintenance concerns and social pressures associated with the immediacy of a request.