OBSERVING STIMULUS SOURCES THAT SIGNAL FOOD OR NO FOOD¹

Abstract

Pigeons were given a choice between observing a stimtllus source that was uncorrelated with food or one that was informative. The informative source wvas either positive, in which a stimulus change signalled food, or negative, in which change signalled no food. If observing is supported by the reduction of uncertainty, the negative as well as the positive source should be preferred to the uncorrelated source. On the other hand, if observing requires support by conditioned reinforcement, the negative source should not be preferred to the uncorrelated source. Two keys served as stimulus sources in a discrete trial procedure. The keys were lighted together, remained on for a variable length of time, and went off together. A key could change color 1 sec before going off. In the uncorrelated source, the change occurred equally often on trials ending twith or without food. In the positive information source, the change occurred only on food trials, whereas in the negative information source, it occurred only on no-food trials. All stimulus changes and food delivery were response independent. As measured by orientation and autoshaped pecking, the positive information source was preferred to the uncorrelated source. However, the uncorrelated source was preferred to the negative information source. The latter result does not support the view that observing behavior is reinforced by the reduction of uncertainty. The positive and negative information sources reduced uncertainty equally but only the positive source provided a signal that could act as a conditioned reinforcer by virtue of its relation to food.It is well established by the experiments of Wyckoff (1952), Prokasy (1956), Bower, McLean, and Meacham (1966, and by more recent work (see Hendry, 1969a), that animals work to observe informative stimuli in preference to uninformative stimuli, even though the informative stimuli do not allow for an improvement in the objective conditions of reinforcement. Two interpretations of this preference have been advanced. One is that observing is maintained by the conditioned reinforcing effect of the stimulus value associated with the more favorable condition of reinforcement (positive value).

The “Where Is It?” Reflex: Autoshaping the Orienting Response

“…Periodic observations revealed that the rats of both groups tended to restrict their activities to parts of the apparatus away from the CS source. Similar withdrawal from a localized CS was also obtained in pigeons when the CS predicted the absence of food (Hearst Sc Franklin, 1977; Jenkins & Boakes, 1973). …”

Consummatory response latency and the stimulus-reinforcer relation in autoshaping

“…A plausible account is that the CS-US relation induces approach tendencies toward cues that predict the US, and withdrawal from cues predicting no-US, relative to uninformative cues, as suggested by our observations (cf. Figure 7) and previous research (e.g., Hearst & Franklin, 1977;Jenkins & Boakes, 1973;Wasserman et al, 1974). These tendencies, in tum, placed the bird at different distances from the food magazine in the present situation, as reflected in latency.…”

DIFFERENTIAL AUTOSHAPING TO COMMON AND DISTINCTIVE ELEMENTS OF POSITIVE AND NEGATIVE DISCRIMINATIVE STIMULI1

“…Other work in autoshaping has revealed that behavior directed toward the stimulus most highly correlated with reinforcement will ordinarily arise if the stimulus is easily localized (e.g., Allaway, 1971;Bilbrey and Winokur, 1973;Brown and Jenkins, 1968;Gamzu and Schwartz, 1973;Williams, 1971, 1973;Jenkins and Boakes, 1973;Peterson, Ackil, Frommer, and Hearst, 1972;Schwartz, 1973;Wasserman, 1973aWasserman, , b, 1974Wasserman, Franklin, and Hearst, 1974;Wasserman and McCracken, 1974). Furthermore, behaviors directed away from a localized stimulus signalling nonreinforcement may also arise in autoshaping studies (see Jenkins and Boakes, 1973;. These autoshaping findings correspond closely with those of operant discrimination studies in which "feature-positive" subjects peck at the distinctive feature and "feature-negative" subjects peck away from it.…”