Hyperactive boys being treated with methylphenidate medication were randomly divided into two groups. In one of the hyperactive groups (n = 18) methylphenidate was withheld for approximately 72 hrs before testing. Boys in the other hyperactive group (n = 20) continued to take their usual daily doses of methylphenidate. Normal boys formed a third group (n = 20). The following electrodermal measures were taken: basal resistance, frequency of non‐specific responses, specific response amplitude to an auditory signal, and number of trials to habituation. Normal and off‐drug hyperactive groups differed significantly on specific response amplitude, and trials to habituation. In addition, frequency of non‐specific responses approached significance. These differences indicated lower reactivity in the off‐drug hyperactive group. Off‐drug and on‐drug hyperactive groups differed significantly on frequency of non‐specific responses. In addition, trials to habituation approached significance. These differences again indicated lower reactivity in the off‐drug hyperactive group.

No abstract

In Exp. I, 22 poor readers and 22 normal readers of elementary-school age were matched on age, IQ, and sex and tested with a visual reaction-time task requiring same-different judgments. On initial trials poor readers were slower than normal readers. In addition, the performance of poor readers deteriorated faster than that of normal readers as testing progressed. In Exp. II, 20 hyperactive boys taking methylphenidate medication, 19 hyperactive boys whose medication was temporarily discontinued, and 19 normal boys were tested. Reaction time on early trials was not significantly different for boys in the on-medication and off-medication groups; however, both hyperactive groups were slower than the normal group. As testing progressed, reaction times of normal boys and boys taking medication remained fairly stable, while the performance of hyperactive boys not taking medication declined. The significance of these results to reading and spelling is discussed.

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.The extensive use of rats for shock-escape and shock-avoidance studies has been accompanied by concern for improved methods of shock delivery (see Dinsmoor, 1966). Ideally, the shock received should be specifiable as to intensity, duration, and bodily locus and should not be modified by any unauthorized escape or avoidance reactions by the rat. The most common method is to deliver shock through the electrified rods of the floor of the experimental chamber.One problem in using electrified rods is that the feces of the animal can cause an electrical short circuit across the rods. Skinner and Campbell (1947) described a method of reducing this problem by mechanically dislodging the feces; Dinsmoor (1958) described a floor-rod arrangement that permitted sufficient spacing between rods to prevent the electrical short circuit.A second problem is that the rat can stand only on rods of the same electrical polarity and thereby avoid shock. A widely adopted solution was devised initially by Skinner and Campbell (1947), who developed a "scrambling" circuit that repeatedly changed the polarity of each grid. As Sloan (1964) has