PubMed Health⌕ Search

Biomedical subjects

M D Beecher

Publications and source records attributed to M D Beecher.

24 records · Page 2Linked to original sources
PubMed1976

Studies on the hearing of the owl monkey (Aotus trivirgatus).

A study was made of the auditory sensitivity of the owl monkey (Aotus trivirgatus). Absolute thresholds for hearing as a function of tone frequency (audibility function) were measured by a behavioral conditioning procedure. The owl monkey's audibility function was found to be more similar to those of other monkeys than those of nocturnal prosimians. It was concluded that the owl monkey's auditory sensitivity cannot be regarded as specialized for nocturnality.

Animals↗
PubMed1971

Rapid acquisition of an auditory localization discrimination by rats.

Acquisition of a sound localization discrimination by rats was investigated. Two loudspeakers were located outside an experimental enclosure containing two levers and a dipper feeder. In the same-side condition, responses on the lever nearest the sound-producing speaker were reinforced. Animals in this condition acquired the discrimination rapidly, generally within the first session. In the opposite-side condition, responses on the lever furthest from the sound-producing speaker were reinforced. Acquisition for animals in this condition began below the chance level (50% correct responses) and took on the order of 10 sessions to approach the final, high level. The course of acquisition in both cases appeared to depend upon an initial tendency of rats to respond on the lever nearest the source of sound in this situation. The rise-decay time of the 4-kHz tone burst signal clearly affected the performance level reached. It did not, however, affect the rate at which the discrimination was acquired.

Animals↗
PubMed1971

Operant conditioning in the bat Phyllostomus hastatus.

Bats of the species Phyllostomus hastatus were trained to press a pigeon key with food as the reinforcer. Patterns of responding under fixed-ratio, fixed-interval, and variable-interval schedules of reinforcement were similar to those typically shown by other species. In a simple auditory discrimination, responding readily came under stimulus control. It is suggested that the behavioral method could be applied to various problem areas of bat behavior.

Animals↗
PubMed1969

Control of responding by the location of an auditory stimulus: role of rise time of the stimulus.

The control of responding by the location of tone bursts of 0.2- or 50-msec rise time was investigated in three albino rats. The apparatus consisted of an enclosure with two levers, two loudspeakers (in different locations), and a dipper feeder. The animal was exposed to tone bursts from either one or the other of the two speakers, and the speaker through which the tone bursts were delivered on any particular trial alternated in an irregular manner. Responses on one lever were reinforced with food in the presence of tone bursts from one speaker; responses on the second lever were reinforced with food in the presence of tone bursts from the second speaker. Responding came under the control of the location of 4-kHz tone bursts of 0.2-msec rise time within the first session. At this rise time, animals maintained a stable level of correct responding of greater than 95%. When the rise time was increased to 50 msec the percentage of correct responding fell to an average of 80 to 85%. It was concluded that location of an auditory stimulus is a powerful controller of responding in rats and that the degree of control is dependent upon rise time.

Animals↗