Bar pressing by the rat as a function of auditory stimulation

Abstract

Fig. 1. Sc hemati c representation of (he functi onal rel at ion between bar pre ssing and noise le vel. level at or below the ambient noise (62 db) level of the room in which the animals were kept produced a steady rate of 2 to 3 bar presses per session with no increment through 10 days. Therefore, four levels of noise were used in the present experiment with increments of 12 db over the ambient noise level, Le., 74, 86, 98 and 110 db re 0.0002 dyne/cm 2.A total of 20 male rats of the Wistar strain were used, five for each group. Each group was subjected to one noise level. For 28 consecutive days prior to the experiment, each of 20 rats was handled for a 10 min. period each day.During any experimental session the rat was placed in the experimental box and exposed for 10 min. to a selected constant level of white noise. If the r at pressed the bar, the noise was interrupted for 15 sec. Depressions of the bar during a 15 sec. quiet period resulted in additional quiet periods of 15 sec.Each group was tested until its frequency of bar pressing reached a constant value. As a result the 74 and 86 db groups were run for 17 consecutive days, and the 98 and 110 db groups were run for 29 consecutive days. ResultsThe results are shown schematically in Fig AbstractThe experiment shows the rate of bar pressing by the rat as a function offour ambient white noise levels, when a bar press interrupts the noise for 15 sec. The results indicate an inverted U'-shaped relation at the beginning of the experiment. As successive exposures to white noise take place, the relation changes progressively to a linear one. These findings support the sensory reinforcement hypothesis, and are discussed in relation to an a priori distinction between stimulus anddrive. It is suggested that the same state may serve as both. Two theoretical explanati ons can explain these findings. ProblemBarnes & Kish (1957) have shown that when depression of a platform interrupts a white noise, rats exposed to the noise will spend considerably more time on the platform than rats not exposed to it. Similarly, Lavery & Foley (1963) have shown that rats will press a bar to interrupt white noise. Each of these studies used a specific level of white noise. The purpose of the present experiment was to determine the functional relation between noise level and this type of behavior. The study examined the frequency of bar pressing as a function of the ambient level of white noise, when each bar press interrupted the noise for 15 sec. MethodThe experimental box, 11 in wide, 12 in long, and 8.5 in deep, was made from 0.5 in plywood, with a metal grid floor and ceiling. Thehorizontalpartofa T-shaped metal bar, 3.25 in long, and of square cross section 0.25 in on the side, protruded 1 in into the box through the floor 0.75 in from one end wall. The vertical stem of the T-shaped bar was connected outside the box to a microswitch which was operated by gentle pressure against the T-bar. The microswitch was in turn connected to Hunter timers and an Esterline-Angus recorder.T...

Response contingent auditory reinforcement in the rat

“…The "latency period" before a rapid increase in responding for Sound OFF (see Fig. 1) was also noted by Lavery & Foley (1965). This period can perhaps be attributed to an adaptation to the sound stimulus.…”

A comparison of the reinforcing properties of stimulus onset for several sense modalities.

“…sensory environment. A cursory review of this literature for the rat indicates that both the onset and offset of foot shock (Harrington & Linder, 1962), a dim light (Roberts, Marx, & Collier, 1958) or a tone (Andronico & Forgays, 1962;Lavery & Foley, 1965), the opportunity to run in a wheel (Hundt & Premack, 1963;Kagan & Berkun, 1954), the taste of nonnutritive sweet substances (Young, 1966), the odour of food or amyl acetate (Long & Tapp, 1967), as well as the traditional rewards such as food and water, will all increase the probability of a response and by this criterion they can be considered reinforcing stimuli. However, the reinforcing properties of different stimuli are difficult to evaluate since a variety of experimental situations and procedures has been employed in these demonstrations.…”