Effects of sucrose concentrations on single alternation runway responding in rats

Rats received runway training under alternating reward and nonreward in which rewarded (R) trials provided 32 or 4% sucrose concentration from a drinking tube and nonrewarded (N) trials provided a dry tube or, for half of the rats in the 32% condition, plain water. Both 32 and 4% concentrations yielded faster running on R trials than on N trials; but this effect was reliable only for the 32% condition. Compared to 4% sucrose, 32% sucrose yielded reliably slower running on N trials and unreliably faster running on R trials.     

The effects of parent-presented models and praise on the vocal behavior of their children

The combined and separate effects of parent-presented models and praise on specific vocalizations of three children (15, 17, and 20 months old) were investigated. The frequency of a specific vocalization was higher when parents modeled and praised it than when they did not. In addition, modeling and praise, when used in combination, had a greater effect on the frequency of specific vocalizations than when used separately. Three additional parents were asked to attempt, by any means they wished, to increase the frequency of a specific vocalization by their children. These parents used modeling almost, exclusively, and the children did not exhibit the specific vocalizations as frequently as did the children whose parents were instructed both to model and praise specific vocalizations.     

Selective attention in cerebral palsied and normal children

Noninstitutionalized, educable retarded, spastic cerebral palsied children of two mental age (MA) levels were compared with normal MA controls on a task measuring selective attention and were not found deficient in selective attention. For both the cerebral palsied and the normals there was an increase in selective attention efficiency with an increase in MA. The results support the position that MA rather than chronological age or IQ is the important variable in determining selective attention performance. The results do not support the attention-deficit theory; they do support the argument that institutionalization has a negative affect on attention. The effects of brain damage and retardation on selective attention ability were discussed.Thanks are expressed to Eleanor Rennie, Head Teacher, Robert Massie, Supervisor of Special Education, and E. F. DeFord, Assistant Director, Department of Research for the Richmond Public Schools, Richmond, Virginia. Appreciation is also given to Scott Hamrick, Principal, Jackson Via Elementary School, Charlottesville, Virginia. Susan Autrey is also thanked for assistance in data collection.     

The misperception of angles: Estimating the vertex of converging line segments

Estimates of the point of intersection of converging line segments depended upon the angle between lines and the orientation of the display. Main conclusion: The tilt of a line is perceptually altered to appear more nearly parallel to the more closely aligned axis, either horizontal or vertical, of an O’s visual field.     

Searching for targets: The effects of specific practice

This study contrasts the effects of specific practice vs nonspecific practice in scanning for sets of five-letter targets. Ss were required to search for new targets after extended practice with one specific target set. Simultaneous memory search was not supported, since searching for one item remained faster than for several items. Serial exhaustive memory search was not supported since the search data were nonlinear. There is evidence that the categorization of a target, even after large amounts of specific practice, is not heavily dependent upon its physical features. A strategy change was detected during practice which allowed more efficient search. It is concluded that a single memory search process can account for the data under both high and low levels of specific practice.     

Contour displacements and tracking errors: Probing ’twixt Poggendorff parallels

Explanations of the Poggendorff effect were tested by varying the separation between outer parallels and by adding interior parallels. Error decreased with the addition of interior parallels, which can be explained by repulsion of parallels. A strong linear trend existed for judgmental error in millimeters plotted against separation between outer parallels. The nonzero intercept of a best-fit line and the slight nonlinearity of the data suggest a hypothesis of contour repulsion between parallels at moderate separations coupled with mistracking of the transversal across the region between parallels. Since the Poggendorff effect was independent of viewing distance, perceptual errors cannot be explained by purely peripheral mechanisms. A true intersection between transversal and parallel was the most critical feature of a display. Inverting a display increased the mean error.     

An integrated model for guiding the selection of treatment components for problem behavior maintained by automatic reinforcement

We evaluated the usefulness of 2 assessments to guide treatment selection for individuals whose prior functional analysis indicated that automatic reinforcement maintained their problem behavior. In the 1st assessment, we compared levels of problem behavior during a noncontingent play condition and an alone or ignore condition. In the 2nd, we assessed participants’ relative preferences for automatic reinforcement and social reinforcers in a concurrent‐operants arrangement. We used the results of these 2 assessments to assign 5 participants to a treatment based on noncontingent access to social reinforcers or to a treatment based on differential access to social reinforcers. We conducted monthly probes with the participants over 10 to 12 months to evaluate the effects of the treatment procedures. All participants showed reductions in problem behavior over this period.     

Individual and combined effects of noncontingent reinforcement and response blocking on automatically reinforced problem behavior

Noncontingent reinforcement (NCR) and response blocking are 2 common interventions for problem behavior maintained by automatic reinforcement. We implemented NCR and blocking with 1 boy and found this combined intervention to be effective at decreasing high rates of automatically reinforced pica. With another child, we compared the effects of blocking alone to the combined intervention. With the third child, we compared NCR alone and blocking alone to the combined intervention. Results showed that the combined intervention was effective at reducing automatically reinforced problem behavior while moderate to high levels of item engagement maintained. When evaluated individually, neither NCR nor blocking was sufficient to reduce problem behavior to clinically significant levels.