Effect of auditory stimuli on performance
under cone VI VI reinforcement schedules
: Type of auditory stimulus and reinforcement schedule
The addition of a concurrent punishment schedule to a choice situation under a concurrent reinforcement schedule generally has two effects (de Villiers, 1980; Farley, 1980; Yoshino, 1986; Yoshino & Kimura, 1991). One is an overall suppressive effect on response rates, similar to the suppressive effect that occurs on a single operant schedule; the overall am ount of responding em itted w ith the addition of a punisher is lower than that in a situation without punishment. A nother effect of the a d d itio n of punishm ent is to enhance sensitivity to reinforcem ent allocation. A preference shift tow ards the richer alternative (i.e. overmatching) is usually observed w hen a concurrent punishm ent schedule is added to a choice situation. If the relationship betw een response rate ratios and reinforcem ent rate ratio is
described in terms of the Generalised M atching Law (GML) (Baum, 1974; 1979; Davison & McCarthy, 1988), the slope value of the linear regression line during punishm ent is higher than it is during reinforcement.
A lthough some specific theoretical issues concerning aversive regulated behaviour have provoked some recent studies (de Villiers, 1980; 1982; Davison & McCarthy, 1992), interest in an aversive regulated behaviour has declined over recent years (Baron, 1991; Pierce & Epling, 1995). This decline in interest m ay have been caused, in part, by issues revolving around animal ethics, especially the use of an electric shock (Pierce & Epling, 1995). It m ay help progress in the research dom ain if an alternative stimulus to an electric shock could be found, and the conditions specified under which such an alternate stimulus is effective as a positive punisher.
As noted in Chapter 1, a loud auditory stim ulus m ay be a candidate for an alternative punisher. Several sets of researchers have dem onstrated the suppressive effect of a tone on responses (McAdie, Foster, & Temple, 1996; Reed, Collinson, & Nokes, 1995; Reed, Mitchel, & Nokes, 1996). McAdie et al. (1996) show ed an aversive property of a loud stimulus by dem onstrating a consistent response bias aw ay from the sound in a choice situation in hens. Reed et al. (1995; 1996) also show ed a suppressive effect of tone on responding u nder extinction w ith the addition of response contingent-tone presentations.
However, it is not clear w hether such a loud auditory stim ulus w o u ld have aversive properties similar to those of an electric shock (in a choice situation) if it were applied to both alternatives under a concurrent reinforcem ent schedule. The
studies show ing a suppressive effect of a tone em ployed a tone presentation schedule only for one alternative of the two available (McAdie et aL, 1993; 1996; Reed et aL, 1995; 1996). In studies using shock, the punishm ent is applied to both alternatives. It is also not clear whether a loud auditory stimulus has the other effect on responding in choice situations observed in experiments using an electric shock (i.e. an alteration in the sensitivity to reinforcement allocation) because no empirical investigation has used a tone in this matter.
In contrast to the above studies show ing a suppressive effect of a tone, some other researchers have demonstrated a facilitative effects (or even no effect) of a tone on responding (Andronico & Forgays, 1962; Symmes & Leaton, 1962). Andronico and Forgays (1962) found increased response rate during a continuous reinforcement schedule with response-contingent tone presentations. Symmes and Leaton(1962) show ed that a loud tone had no effect on responding in three experiments. These apparently divergent results rem ain in need of explanation if a loud auditory stim ulus is to be utilised as a punishing stimulus.
Comparison of the procedures employed in these experiments suggests that, at least, two aspects of the procedures m ay be critical in generating the divergent results; the type of a loud auditory stimulus used, and the schedule of reinforcem ent u sed to m aintain the responding. W ith respect to the first of these procedural differences, Reed et al. (1995) show ed that a click m ay have a facilitative effect on the level of responding under a reinforcement schedule; whereas, on the contrary, a tone had a suppressive effect. McAdie et al. (1993) showed that the types of sound used m ay affect differentially the extent of the observed response bias.
The second procedural difference concerns the reinforcem ent schedule that maintains responding in order to examine the effect of an auditory stim ulus. Reed et al. (1995) show ed that the click had a suppressive effect on the responding level u n d e r an extinction schedule, but had a facilitative effect u n d er a reinforcem ent schedule. Andronico and Forgays (1962) reported a facilitative effect of a tone on responding under a continuous reinforcement schedule, whereas, Reed et al. (1995; 1996) reported a suppressive effect of a tone under an extinction schedule. These results suggest that the same type auditory stimulus m ay have divergent effects according to the schedule that maintains responding.
Given the above, the current studies were conducted in order to investigate the substitutability of a loud auditory stimulus for an electric shock. Specifically, the present studies attem pted to examine the effect of an auditory stim ulus on the level of responding in a choice situation. The different effects of various type of an au d ito ry stim uli was focussed on in Experiment 2.1, and the effect of the reinforcement schedule that m aintains responding was focussed on in Experiment
2.2.
Experiment 2.1 Effect of type of auditory stimuli on performance under cone VI