PubMed Health⌕ Search

Biomedical subjects

R G Weisman

Publications and source records attributed to R G Weisman.

At least 19 recordsLinked to original sources
PubMed2000

Call-note discriminations in black-capped chickadees (Poecile atricapillus).

Bioacousticians (M.S. Ficken, S. R. Ficken, & S. R. Witken, 1978) classified black-capped chickadee call notes from the chick-a-dee call complex into 4 note types (A, B, C, and D) identified from sound spectrograms. In Experiment 1, chickadees (Poecile atricapillus) learned operant auditory discriminations both within and between the 4 note types but learned the between note-type discrimination significantly faster. In Experiment 2, when the original, unrewarded between-category exemplars were replaced with novel, rewarded exemplars of these same categories, chickadees showed transfer of inhibitory stimulus control to the novel exemplars. In Experiment 3, when novel exemplars were replaced by the original exemplars, chickadees showed propagation of positive stimulus control back to the original exemplars. This evidence suggests that chickadees and bioacousticians accurately sort conspecific call notes into the same open-ended categories (R. J. Herrnstein, 1990).

Animals↗
PubMed1994

Effect of motivational context on conspecific song discrimination by brown-headed cowbirds (Molothrus ater).

Two experiments to examine the effects of motivational context on the perception of conspecific song by cowbirds were conducted. In the first experiment, sexual displays were elicited from females by playback of normal song and rearranged sequences of the component phrases. In a second experiment, male and female cowbirds discriminated among the same songs in a food-rewarded operant procedure. In a sexual context, the birds were sensitive to both the beginning and end phrases of normal song, whereas in a food context, the birds were more sensitive to the beginning of normal song. In both experiments, one-phase songs were better discriminated from normal song than two-phrase songs, and there was no effect of phrase order on discrimination. Similarities and differences in the results of the two experiments suggest that some aspects of cowbird song perception remain constant across motivational contexts, whereas others are unique to particular motivational contexts.

Acoustic Stimulation↗
PubMed1986

Song sequence discrimination in the black-capped chickadee (Parus atricapillus).

Captive black-capped chickadees (Parus atricapillus) were presented with normal and altered versions of their species-specific "fee bee" song, to determine how note type, number, and sequence affect recognition. The number of perch changes and vocalizations (analyzed separately) given in response to playback did not differ reliably as a function of song type, whereas latency to first vocalization after playback did. In an initial experiment using two-note songs, birds vocalized sooner to songs beginning with fee than with bee and to fee bee than to fee fee. In a second experiment, birds were presented with shortened (single note), normal, and lengthened (three note) songs each consisting of a single-note type (either fee or bee). Habituation slowed responding to altered songs but not to fee bee over three test sessions. Results from the first session suggest that chickadees distinguished single fees and three-note songs from normal song, single fees from single bees, and two-note songs from three-note songs. Results from the third session suggested that chickadees distinguished normal song from any of the altered songs. The internal representation of conspecific song in the chickadee thus distinguishes between fee and bee notes, contains information about note order, and is sensitive to note number. The pattern of responses is consistent with a model of recognition based on note-by-note integration of individual decisions about song structure.

Animals↗
PubMed1986

Behavioral effects of cyclic dosing with methylmercury in pigeons.

The present experiments examined the effects of cyclic dosing with methylmercury (MeHg) on some psychological functions in pigeons. A delayed sequence discrimination task involving order competency and a feeding task involving perceptual motor skill were tested in pigeons dosed with 2.0 mg/kg, 0.5 mg/kg, or no MeHg (the control group) during cycles of brief daily MeHg exposure and extended behavioral testing. Performance in the sequence discrimination and the feeding task was affected after a cumulative dose of only 20 mg/kg in the 2.0 mg/kg group. Sequence discrimination recovered within three months after dosing when MeHg was stopped, but feeding skill did not recover over the remainder of the experiment (about 4 1/2 months later). A cumulative dose of 86 mg/kg in the 0.5 mg/kg group had no observable effect on either task.

Animals↗
PubMed1978

Acceleration and suppression of rats' responding to avoid foot shock and tail shock.

Signalled response-independent shocks were superimposed on rats' wheel-turn responding to avoid shock administered to their feet through a grid floor or to their tails through fixed electrodes. In Experiment I, a tone paired with response-independent foot shock increased responding in three of four rats; a tone paired with tail shock increased responding in only one of four rats and suppressed responding in two rats. In Experiment II, a tone presented randomly with respect to response-independent shock had no reliable effect on responding to avoid foot shock or tail shock. In Experiment III, tail shock and foot shock were compared in a within-subject design while the temporal pattern of responding during conditioned stimuli was recorded. Responding during the conditioned stimulus preceding foot shock was characterized by initial suppression of responding at tone onset, followed by increased responding just before response-independent shock. Responding was suppressed throughout the conditioned stimulus preceding tail shock. Foot shock elicited bursts of responding, but tail shock did not.

Journal Article↗
PubMed1977

Selective punishment early and late in fixed-ratio schedules of food reinforcement.

Pigeons key pecked for grain on a fixed-ratio 100 schedule; electric shocks occurred intermittently at the fifteenth or eighty-fifth response in the ratio. In Experiment I, shock was at the fifteenth response for two birds, and at the eighty-fifth response for two others, in every sixth, twelfth, or eighteenth ratio. Rate of responding decreased as frequency of shock increased, and the pattern of responding included an increased initial pause and low rates or pause-run sequences that extended further into the ratio when shock was at the fifteenth response than when it was at the eighty-fifth response. Shock early in the ratio engendered longer initial pauses than shock late in the ratio. In Experiment II, four birds responded on a two-component multiple schedule in which shock occurred at the fifteenth response of the third ratio in the presence of a white keylight and at the eighty-fifth response of the third ratio in the presence of a green keylight. The overall rates of responding decreased as shock intensity increased. All four birds responded differentially to the white and green keylights, but with a pattern that varied between birds. In general, punishment reduced the probability of responses that preceded it, regardless of the ordinal position of those responses. Both studies confirm that the probability of responding is reduced less by aversive stimuli produced late in a fixed-ratio than by aversive stimuli produced early in a fixed-ratio.

Journal Article↗
PubMed1976

Dimensional stimulus control following brief wavelength training.

Pigeons with extensive training pecking a key illuminated by a white line then had brief training with the key illuminated by 555 nanometers. This was immediately followed by a wavelength generalization test in extinction. Dimensional stimulus control about the training wavelength increased with the duration and number of reinforcements given on variable-interval 30-sec and variable-interval 10-sec schedules in Experiment I. In Experiment II, dimensional stimulus control was obtained after only 4 min of wavelength training from birds with prior and independent discrimination training. Experiment III provided groups equated in number of reinforcers with groups in Experiment I and two 8-min duration groups. Analyses, which included results from both Experiments I and III, showed that dimensional stimulus control increased: (a) more rapidly as a function of the duration of variable-interval 10-sec than variable-interval 30-sec reinforcement; (b) at the same rate across variable-interval reinforcement schedules, as a function of the number of reinforcers available during brief wavelength training.

Journal Article↗
PubMed1975

Response-dependent shock in second-order fixed-ratio schedules of food presentation.

Three pigeons key pecked under second-order schedules in which the completion of two successive fixed-ratio 50 components constituted a reinforcement cycle. Tandem, chained, and brief-stimulus second-order schedules were studied when completion of the initial fixed-ratio 50 component delivered brief intense electric shock in every nth reinforcement cycle and n assumed values between one and nine. During sessions without shock, the brief-stimulus (unpaired with food) schedule generated higher rates of responding in the initial component than did the tandem schedule. Electric shock engendered increased time to the fifth response and a repeated pause-run pattern of not responding and responding, particuuarly in the initial component, even with shock scheduled in every ninth reinforcement cycle. The results were consistent with those reported for shock of a shorter duration scheduled in every reinforcement cycle. The overall rate of responding decreased as a function of increasing shock density and was lower in brief-stimulus than in tandem schedules.

Journal Article↗
PubMed1973

Discrimination of a response-independent component in a multiple schedule.

Pigeons were trained to respond in non-differential reinforcement pre-discrimination training, with a multiple variable-interval 1-min variable-interval 1-min schedule. Each bird then received discrimination training with a multiple variable-interval 1-min variable-time 1-min schedule. Thus, discrimination training was between response-dependent (variable-interval) and response-independent (variable-time) schedules with the rate of reinforcement equated. In Experiment I, only three sessions of non-differential reinforcement preceded discrimination training and for half the birds, a 0 degrees line was correlated with the response-dependent schedule; for the remaining birds the 0 degrees line was correlated with the response-independent schedule. Post-discrimination gradients of excitatory stimulus control were obtained from the former group, while the latter group showed little evidence of post-discrimination stimulus control by the 0 degrees line. Differential responding to the variable-time schedule was not accompanied by behavioral contrast to the variable-interval schedule. In Experiment II, 20 sessions of non-differential reinforcement preceded discrimination training and the 0 degrees line was correlated with variable-time reinforcement for each bird. Differential responding to the 0 degrees line was accompanied by negative induction to the variable-interval schedule and by inhibitory stimulus control about the 0 degrees line during a post-discrimination generalization test.

Journal Article↗
PubMed1970

Factors influencing inhibitory stimulus control: differential reinforcement of other behavior during discrimination training.

Pigeons were trained to respond on a multiple variable-interval 1-min variable-interval 1-min schedule, then switched to a multiple variable-interval 1-min differential-reinforcement-of-other-behavior discrimination training. The rate of reinforcement was held constant during the shift from non-differential reinforcement to discrimination training. Behavioral contrast and post-discrimination inhibitory stimulus control followed the observation of a reduction in the rate of responding to the stimulus correlated with reinforcement for the non-occurrence of pecking.

Journal Article↗
PubMed1969

Factors influencing inhibitory stimulus control: discrimination training and prior non-differential reinforcement.

In Exp. I, shallow U-shaped gradients of inhibition in the line-orientation dimension were obtained from birds that had a vertical (0 degrees ) line on a green surround correlated with extinction and a blank green surround correlated with reinforcement. Birds that had massed extinction in the presence of the 0 degrees line showed flat gradients. Thus, discrimination training, but not massed extinction, appears to generate inhibitory control. In Exp. II, as in studies of control by a stimulus correlated with punishment, non-differential training across the line-orientation dimension preceded further sessions. Steep inverted gradients about the 0 degrees line were obtained after discrimination training with the 0 degrees line correlated with extinction. Gradients obtained after massed extinction tended to be flat. Again, discrimination training was critical in obtaining negative gradients of stimulus control.

Journal Article↗
PubMed1969

Some determinants of inhibitory stimulus control.

Interspersed reinforcement and extinction during discrimination learning generate a U-shaped gradient of inhibition about the stimulus correlated with extinction. The present work showed that extinction is not a necessary determinant of inhibitory stimulus control. In Exp. I, a reduction in the rate of reinforcement, through a shift from a multiple variable-interval 1-min variable-interval 1-min schedule to a multiple variable-interval 1-min variable-interval 5-min schedule, resulted in a post-discrimination line orientation gradient of inhibition about the stimulus correlated with the variable-interval 5-min schedule. In Exp. II, the rates of reinforcement, correlated with a pair of stimuli, were held constant during a shift from a multiple variable-interval 1-min variable-interval 1-min schedule to a multiple variable-interval 1-min differential-reinforcement-of-low-rate schedule. Inhibitory stimulus control about the stimulus correlated with the differential reinforcement of low rate was obtained. In both experiments, a reduction in the rate of responding during one stimulus and behavioral contrast during the other stimulus preceded the observation of inhibitory stimulus control.

Journal Article↗