Thesis (Ph. D.)--University of Wisconsin--Madison, 1950. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph.D.)--Boston University. / Gradients of extinction were determined for an instrumental response, with circle size as the stimulus dimension. The Ss were 69 albino rats. All animals were given equal training in a runway to each of three stimuli, consisting of metal disks painted white and having areas of 20 cm2 , 40 cm2, and 79 cm2, respectively. After the training series of 30 trials, 27 animals were given 10 extinction trials to the 20-om2 circle, and 30 animals, to the 79-om2 circle. Each animal was then given a test-extinction series of 20 trials to one of the three stimuli, with approximately equal groups assigned to each stimulus. A control group of 12 animals was given both preliminary and test-extinction series to the 40-om2 circle [TRUNCATED].

This thesis discusses the valence of stimulus material as a variable in incidental learning.

The present study investigated the use of stimulus-stimulus pairing (SSP) as the first step to build an echoic repertoire with children with no vocal communication skills. We began with echoic probes to establish the child did not have the target sound in their echoic repertoire, then implemented SSP to increase the rate of the target vocalization, and systematically added direct reinforcement, and a delay, until the participant responded in 80% of trials; we then implemented echoic training. We conducted this procedure with 3 young children with autism. This procedure was effective for one of three participants, and her echoic learning history immediately generalized to other sounds. For the other two participants, SSP increased the rate of vocalizations; however, they did not respond in enough trials to move to echoic training before withdrawing from the study. This study provides preliminary evidence for the use of SSP as part of echoic training for children with limited functional communication.

A computerized program was designed to test whether arranging a common element in two, otherwise independent, 2-term correlations (stimulus-stimulus and response-stimulus) would result in emergent simple discriminative-stimulus properties for the antecedent stimulus relative to an arrangement with no common elements programmed. Data from 8 adult participants in this experiment indicate that common element arrangements led to relatively high rates of responding in the presence of the putative discriminative stimulus and relatively low rates or no responding in the presence of the putative s-delta during testing in extinction. Conversely, the uncommon element arrangements produced no clear discriminative control. The current data reflect a comparison of arrangements across subjects. These data support Sidman's (2000) suggestion that common elements among contingencies are sufficient to produce stimulus classes and cause class mergers. The data also have implications for thinking about the mechanism by which and the conditions under which discriminative control develops. Finally, these data have the potential to inform the programming and implementation of reinforcement contingencies in applied settings.

No description available.

No description available.

No description available.

No description available.

A study of the binocular accommodation response is presented for normal and amblyopic observers to selected stimulus conditions using a binocular infra-red optometer and a commercially-available autorefractor. The work reviews the neural control of the near triad and discusses the historical development of models of mutual interaction between accommodation and convergence, presenting experimental evidence to support or refute each proposition. The basic characteristics of the accommodation response are reviewed along with the influencing factors. A central feature of this work is the evaluation of the correlation present between the eyes for both step-wise changes in target vergence and steady-state viewing. Reaction times for visually normal subjects were found to be similar to those found by previous workers and were independent of both size and direction of the step change. Response times for a mean step size of approximately 2.5D exhibited a marked degree of intersubject variability, particularly for the decreasing response and were step-size dependent. Eye dominancy was not found to be a significant factor in the overall response time. The binocular accommodation responses were found to have a high level of correlation to step-wise changes in target vergence. This in, itself, is perhaps not surprising in view of the anatomical similarities between the eyes and the relatively large dioptric changes induced. To obtain a clearer picture of the control of accommodation assessment of the microfluctuations was necessary. A high degree of correlation between amblyopic eyes and their fellow normal eyes is reported for both reaction and response times, although response times are longer than those for normal eyes. Reaction times for four subjects were not significantly different to those of the dominant eye. The subject presenting with the deepest amblyopia did have a significantly increased reaction time and a relationship with minimum angle of resolution is considered. Steady-state viewing shows the microfluctuations to have a high level of coherence, suggesting the control of accommodation to be at or above the point at which the IIIrd nerves are conjoint. Increasing target vergence causes an increase in the rms amplitude of the microfluctuations, binocular viewing not influencing the response characteristics. As target luminance decreased, rms values and low frequency drifts increased. Amblyopic eyes show an increase in the magnitude of the low frequency components of the microfluctuations for moderate to high stimulus vergences. The presence of different behaviour to that observed in normals supports a role for the microfluctuations. The response of amblyopic eyes to coloured stimuli results in an increase of the low frequency component to targets at the extremities of the visual spectrum, furthering the argument for a positive role for the fluctuations. The steady-state response to coloured stimuli differed from that found in normal eyes in that the appropriate response to overcome the chromatic interval was not observed for moderate to high stimulus vergences. The overall anomalous response could not use the additional information provided by coloured targets. Finally the detectibility of defocus was tested with sine waves and using signals derived from the microfluctuations. The threshold of detection for the microfluctuations is similar to that for sine waves, but is thought to be due to the presence of discontinuities and abrupt shifts in the response level. This adds support to Crane's(1966) hypothesis of 'accommodative saccades'.