Susan H. Chung

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Pigeons were trained to peck for food reinforcement, and the minimum effective force for a peck was varied. In a single-key situation, the response rate was unaffected up to a certain force value, beyond which increments caused a proportional decrement in response rate. Transient enhancement and suppression effects were observed following a change in the(More)
Pigeons were trained to peck either of two response keys for food reinforcement on equated aperiodic schedules. Delays of reinforcement for pecks at one key reduced the relative frequency of pecking exponentially as a function of the delay interval. Similar functions were obtained when other dependent variables were plotted against the delay interval.
To assess speed- and gait-related changes in semitendinosus (ST) activity, EMG was recorded from three cats during treadmill locomotion. Selected step cycles were filmed, and hip and knee joint kinematics were synchronized with EMG records. Swing-phase kinetics for trot and gallop steps at 2.25 m/s were compared for gait-related differences. Also, swing(More)
Pigeons were trained to peck either of two response keys for food reinforcement on equated aperiodic schedules. The distribution of responding at the two keys was studied as reinforcement was delayed for various durations. The relative frequency of responding at each key was shown to match the relative immediacy of reinforcement, immediacy defined as the(More)
When a variable-interval schedule of reinforcement was segmented into small fixed-interval components, with reinforcements following some components and brief blackouts following the others, rate of responding doubled and a positively accelerated pattern within each component was obtained. Presented according to this percentage reinforcement paradigm, the(More)
A molecular association between chloroform and sulfur dioxide in the gas phase at room temperature was studied by Fourier transform infrared spectroscopy. Since the intensity of the CH-stretching fundamental vibration of monomer chloroform is very weak but much stronger upon complexation, a simple subtraction procedure isolated the CH-stretching vibration(More)
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