The relation of multiple-schedule behavioral contrast to deprivation,time in session,and within-session changes in responding

Pigeons' keypecking was reinforced by food on baseline schedules of multiple variable interval (VI) x VI x and on contrast schedules of multiple VI x VI y. Deprivation of food was varied by maintaining subjects at 75%, 85%, and 95% (+/- 2%) of their free-feeding weights. Positive and negative behavioral contrast were observed. The size of the contrast was not systematically altered by changes in deprivation. Positive and negative contrast were both larger later in the session than they were earlier. Within-session decreases in responding were steeper for the baseline than for the contrast schedules for positive contrast. Within-session decreases were steeper for the contrast than for the baseline schedules for negative contrast. These results were predicted by the idea that different amounts of habituation to the reinforcer during the baseline and contrast schedules contribute to behavioral contrast. The results show that contrast occurs under conditions that reduce the effect of the following component. The results support the assumption that positive and negative contrast are produced by symmetrical theoretical variables.     

Patterns of Social Interaction of Mainstreamed Preschool Children: Hopeful News from the Field

Much of the research on social interaction in mainstreamed settings has focused on “reverse mainstreamed” or special environments in contrast, the present study observed 600 social interactions in 19 regular preschools. Three findings emerged: a) retarded children are substantially integrated into the emotional and social life of the peer group, but not fully integrated into peer group verbal life; b) there is an inverse relationship between teachers’ initiation of social interaction with retarded children and the degree to which the latter are integrated into peer group life; and c) teachers provide retarded children with more verbal enrichment and emotional protection than these children receive from their peer group. On balance, these findings are fairly encouraging, suggesting that to a considerable extent mainstreaming is working in preschool classrooms.     

Developmental issues in cognitive mapping: the selection and utilization of environmental landmarks

2 studies were conducted to investigate developmental differences in the ability to select and use environmental landmarks for cognitively organizing distance information from a walk. In experiment 1, second-grade, fifth-grade, and college subjects viewed a simulated walk and selected scenes that were high in potential landmark value. In experiment 2, children from the same grade levels first viewed the walk and then ranked distances among either the test scenes most frequently selected by their peers or those selected most frequently by adults. Results indicated that (a) adults and children may not spontaneously select the same features as real-world landmarks; (b) children are less capable than adults in judging the value of potential landmarks as distance cues; and (c) the ability to use environmental landmarks as cues for distance information developmentally precedes the ability to assess this potential information value.     

How infants use vision for grasping objects

The role of vision was examined as infants prepared to grasp horizontally and vertically oriented rods. Hand orientation was measured prior to contact to determine if infants differentially oriented their hands relative to the object's orientation. Infants reached for rods under different lighting conditions. Three experiments are reported in which (1) sight of the hand was removed (N = 12), (2) sight of the object was removed near the end of the reach (N = 40, including 10 adults), and (3) sight of the object was removed prior to reach onset (N = 9). Infants differentially oriented their hand to a similar extent regardless of lighting condition and similar to control conditions in which they could see the rod and hand throughout the reach. In preparation for reaching, infants may use the current sight of the object's orientation, or the memory of it, to orient the hand for grasping; sight of the hand had no effect on hand orientation.     

Integration of reinforcement effects over time

Two accounts of how density of reinforcement affects steady-state performance on probabilistic schedules were compared: the real-time linear operator (RTLO) model and a temporal control model (in which response strength is determined by reinforcement probability as a function of postreinforcement time). In Experiment 1, the probability of reinforcement repeatedly cycled between extinction and a random-ratio 10 schedule. Response-rate gain and phase did not change with period of the cycle as predicted by the RTLO model, nor did either model predict the differences in response rate following reinforcement at different points in the cycle. In Experiment 2, the probability of reinforcement was elevated immediately following a reinforcement but fell after a few seconds. Previous reinforcements had no effect upon responding. An extension of the temporal control model, the cumulative impulse model, allowed for the summing of response strength over successive reinforcements and was consistent with the data of both experiments.     

Sameness-difference judgments inSaimiri sciureus based on volumetric cues

The rationale was to apply Piaget’s theory and methods to the study of the phylogenetic development of cognitive abilities. It was asked whether squirrel monkeys have the prerequisite skills for conservation of quantity, and, specifically, whether they might respond differentially to equivalent and unequivalent volumetric cues. All monkeys responded significantly and differentially to pairs of identical objects or pairs of objects similar only in volume vs. pairs of objects which differed in volume. It was concluded that squirrel monkeys have the prerequisite skills for the conservation of quantity. Discussion included methodological problems associated with demonstrating conservation in nonhumans as well as the potential usefulness of Piaget’s theory for phylogenetic studies of intelligence.     

Developing local oral reading fluency cut scores for predicting high‐stakes test performance

This study evaluated the classification accuracy of a second grade oral reading fluency curriculum‐based measure (R‐CBM) in predicting third grade state test performance. It also compared the long‐term classification accuracy of local and publisher‐recommended R‐CBM cut scores. Participants were 266 students who were divided into a calibration sample (n = 170) and two cross‐validation samples (n = 46; n = 50), respectively. Using calibration sample data, local fall, winter, and spring R‐CBM cut scores for predicting students’ state test performance were developed using three methods: discriminant analysis (DA), logistic regression (LR), and receiver operating characteristic curve analysis (ROC). The classification accuracy of local and publisher‐recommended cut scores was evaluated across subsamples. Only DA and ROC produced cut scores that maintained adequate sensitivity (≥.70) across cohorts; however, LR and publisher‐recommended scores had higher levels of specificity and overall correct classification. Implications for developing local cut scores are discussed.     

Two-Year-Old Children's Sensitivity to a Parent's Knowledge State When Making Requests

These studies examined whether toddlers take their communicative partners' knowledge states into account when communicating with them. In Study 1 , 16 2-year-old children (mean age 2-7) had to ask a parent for help in retrieving a toy. On each trial, a child was first introduced to a new toy that was then placed in 1 of 2 containers on a high shelf. The parent either witnessed these events along with the child or did not because she or he had left the room or had covered her or his eyes and ears. As predicted, when asking for help in retrieving the toy, children significantly more often named the toy, named its location, and gestured to its location when a parent had not witnessed these events than when she or he had. In Study 2, 16 2-year-old children (mean age 2-3) had to ask a parent for help in retrieving a sticker dropped into 1 of 2 identical containers placed out of reach in the far corners of a table. The parent either witnessed, along with the child, which container the sticker was dropped into or did not because her or his eyes were closed. In their requests for help, young 2-year-old children gestured to the sticker's location significantly more often when the parent did not know its location than when she or he did. The implications of these findings for current characterizations of 2-year-old children's ability to assess the knowledge of others is discussed.