Opportunity for Interaction as Reinforcement in a T-maze

Abstract

Two forms of handling were used as reinforcement in a T-maze for 34 albino rats. In a twelve-day experiment, those receiving gentling learned to avoid reinforcement while those receiving fondling learned to obtain it. In a six-day follow-up, rats were given either a fondling hand or a rat companion as reinforcement.The proportion of reinforced trials and running times were similar for both objects. Rats learned a task to obtain interaction with a rat or responsive surrogate. Werner and Latan6 (1974) have argued that responsive interaction is an important basis of social attraction in albino rats. They demonstrated that rats were attracted to a responsive fondling human hand, spending upwards of 60% of a five minute test period in contact with this social surrogate. The kind and amount of interaction was comparable to rats behavior with rat companions. This finding conflicts with a series of studies in which gentling--a form of handling similar to fondling--was found to be aversive to rats. Animals learned left-right and black-white discriminations, as well as reversal problems in order to avoid gentling (Candland et al., 1960;Candland et al., 1962). Although the two are similar, there are enough differences between gentling and fondling that it is possible one is aversive and the other attractive.The purpose of the present experiment is, in Part 1, to resolve this conflict by using these two methods of reinforcement in Candland et al's (1960) paradigm, and, in Part 2, to replicate Werner and Latane in a different apparatus.Werner and Latane found it was necessary to familiarize the rats with fondling before a hand was attractive. Consequently, preexperimental treatment was manipulated, with one third of the rats fondled, one third gentled, and one third not treated prior to testing. Part 1. Method. Thirty-four albino rats were tested in a leftright discrimination problem for 12 days. A 3x2 factorial design described their pretest experience (Prefondled/Pregentled/Nonhandled) and their reinforcement during testing (Fondling/Gentling).Subjects and Preexperimental Treatment. Thirty-six naive male albino rats (Sprague-Dawley) were 30 to 50 days of age when received from the university vivarium and randomly assigned to treatment conditions 21 days prior to testing. All were housed alone in standard single cages, food and water ad lib. Prior to testing two animals died, leaving 34 subjects.During the three week preexperimental period, designated animals were prehandled for 5 minutes per day. In fondling, the Experimenter pulled the cage out slightly and reached into the cage to stroke, scratch, and fondle the rat. Rats were free to move around the cage away from and toward the hand. In gentling, the experimenter held a rat in one hand and stroked in a cephalocaudal direction at about 50 strokes per minute. Between rats, hands were washed in a vinegar and water solution to keep odors from previously handled rats from exciting others.

Human-based social interaction can reward a rat’s behavior

“…Our results and similar ones reported by Werner and Anderson (1976) are in direct conflict with much of the "gentling" literature mentioned above. Collectively, they suggest that although some forms of human-rat interaction may be aversive to the rat, there are at least some interactions between human and rat that are positive enough to modify the rat's behavior in the absence of conventional food reward.…”

“…In one such study (Werner & Latane, 1974), an experimenter's hand movements attempted to simulate rats at play by "poking, lifting, rubbing and scratching, tapping and tumbling." These researchers concluded that contact with the human hand was as attractive as contact with another rat, thereby suggesting that a human-rat interaction can be a preferred activity (Werner & Anderson, 1976;Werner & Latane, 1974).…”

Individual Differences and Social Influences on the Neurobehavioral Pharmacology of Abused Drugs

“…Initiation of drug taking nearly always occurs in a social context in which peers provide social reward for the behavior, yet surprisingly little research has been conducted with animal models to investigate the influence of social interactions at the time of drug taking (i.e., social context). The presence of a nonthreatening conspecific is highly salient and rewarding, especially in adolescent rats (Vanderschuren et al, 1997;Spear, 2000); for instance, nonthreatening conspecifics 1) elicit approach (Panksepp et al, 1984), 2) elicit ultrasonic vocalizations thought to be indicative of positive affect (Burgdorf et al, 2008), 3) are positive reinforcers (Angermeier et al, 1959;Werner and Anderson, 1976;Evans et al, 1994), and 4) produce CPP (Calcagnetti and Schechter, 1992;Crowder and Hutto, 1992;Douglas et al, 2004). Research examining drug effects in a social context suggests that this is an important variable that influences sensitivity to the rewarding effects of drugs.…”

Playful handling by caretakers reduces fear of humans in the laboratory rat

“…Although Maurer et al (2008) reported that use of their gentling technique reduced the fear of laboratory rats towards humans, it is not clear which aspects of the procedure had the most impact on fear reduction. Other studies have indicated aversive responses, or absence of effects, when some of these techniques were used individually (e.g., Brudzynski and Ociepa, 1992;Burgdorf and Panksepp, 2001;Cloutier and Newberry, 2008;Werner and Anderson, 1976). Furthermore, provision of food treats is contraindicated in some studies due to conflict with research objectives, and is not always effective in mitigating the stressfulness of procedures (Cloutier and Newberry, 2008).…”