A rat chamber and electrode procedure for avoidance conditioning

A method was developed for studying the reactions of rats to aversive shock. The distinctive features were the design of the chamber and a method of restraint that allowed the use of surface electrodes to deliver the shock. Advantages of this method were: (1) accurate specification of the shock actually received by the rat; (2) elimination of all unauthorized escape or avoidance reactions; (3) elimination of the shock scramblers and floor grids required with foot-shock; and, (4) rapid acquisition of performance under various avoidance procedures and various frequencies of shock delivery.     

Effect of shock duration on shock-induced fighting

Shock-induced fighting between paired rats was a direct function of the duration of the shock stimulus. Continued presentations of the shock partially reversed this direct relationship.     

Fixed-ratio punishment

Responses were maintained by a variable-interval schedule of food reinforcement. At the same time, punishment was delivered following every nth response (fixed-ratio punishment). The introduction of fixed-ratio punishment produced an initial phase during which the emission of responses was positively accelerated between punishments. Eventually, the degree of positive acceleration was reduced and a uniform but reduced rate of responding emerged. Large changes in the over-all level of responding were produced by the intensity of punishment, the value of the punishment ratio, and the level of food deprivation. The uniformity of response rate between punishments was invariant in spite of these changes in over-all rate and contrary to some plausible a priori theoretical considerations. Fixed-ratio punishment also produced phenomena previously observed under continuous punishment: warm-up effect and a compensatory increase. This type of intermittent punishment produced less rapid and less complete suppression than did continuous punishment.     

Reflexive fighting in response to aversive stimulation

Reflexive fighting was elicited between paired rats as a reflex reaction to electric shock prior to any specific conditioning. Such fighting was fairly stereotyped and easily differentiated from the rats' usual behavior. The strength of this reflex was not attributable to any apparent operant reinforcement. Elicitation of fighting was a direct function of the enclosed floor area and a nonmonotonic function of the shock intensity.

Failure to scramble the polarity of the electrified grid produced inconsistent fighting. Under optimal conditions fighting was consistently elicited by shock regardless of the rat's sex, strain, previous familiarity with each other, or the number present during shock. Repeated shock presentations did not produce an appreciable decrease in fighting until signs of physical debility appeared. Although shock did not cause a rat to attack inanimate objects, it did produce attack movements toward other small animals. Failure of guinea pigs to defend themselves revealed that the elicitation of fighting from the rat does not require reciprocal attack. Paired hamsters showed fighting reactions similar to those of the rats, whereas guinea pigs failed to fight. Electrode shock and a heated floor elicited fighting between the rats, but intense noise and a cooled floor did not.

     

Behavioral engineering: the reduction of smoking behavior by a conditioning apparatus and procedure

Recent findings from animal conditioning studies have revealed methods of reducing responses to a very low level with a minimum of aversive by-products. These findings were incorporated into the design of a cigarette case that automatically locked itself for a period of time after a cigarette was removed from it. The next cigarette could be taken at the end of the interval, which was signalled by distinctive stimuli. Five heavy smokers were allowed to become accustomed to using the case. Then, the duration for which the case was locked was gradually increased over a period of weeks to about 1 hr. Smoking gradually decreased to the target level of about one-half of a package of cigarettes per day. Control procedures showed that specific features of the apparatus were responsible for the reduction of smoking. The results indicated that this apparatus was sufficiently effective, convenient, and acceptable to smokers to constitute a practical procedure for reducing smoking to the level considered medically safe. The procedure may also have potential for reducing other habit-forming or addictive behaviors.