A procedure for testing position generalization from articulation training

Generalization was repeatedly tested in individual children during an articulation training program which progressed in phases from isolated sound training to medial position training using nonsense syllables and, if necessary, words. Four children who misarticulated the /s/ in initial, final, and medial positions in words comprised the population of the study. If complete generalization on 12 test probes had not occurred after 3 phases of nonsense syllable training, 3 additional phases (initial, final, and medial position) of word training were administered. Training was terminated when (1) complete generalization had occurred or (2) all phases of the program had been administered. Two children generalized completely at the end of nonsense syllable training, one child generalized after nonsense syllable training, word training, and instructions, and the fourth child did not generalize completely by the end of the study. Although the correctly articulated /s/ began to control the children’s responses in untrained contexts, the results showed that position generalization was not a function of the position trained. As the children progressed through the program, generalization increased, but sometimes failed to stabilize on specific items from phase to phase.

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.

Plaque enhancement of enteroviruses by magnesium chloride, cysteine, and pancreatin

Wallis, Craig (Baylor University College of Medicine, Houston, Tex.), Fred Morales, Joycelyn Powell, and Joseph L. Melnick. Plaque enhancement of enteroviruses by magnesium chloride, cysteine, and pancreatin. J. Bacteriol. 91:1932-1935. 1966.-Plaque formation of 21 echoviruses (types 1-6, 9, 13, 15-19, 23-26, 29-32) and 8 coxsackieviruses (B1-6, A7, and A9) was enhanced by increased concentrations of MgCl(2), l-cysteine, and pancreatin in agar overlay medium. In most cases, cationic and anionic polymers (diethylaminoethyl dextran, dextran sulfate, or protamine sulfate) were ineffective. All strains of poliovirus and group B coxsackieviruses were enhanced under agar by MgCl(2). Five of the eight coxsackieviruses tested were also enhanced by cysteine or pancreatin. Certain enteroviruses, which have been difficult to assay by plaque method, can now be quantified effectively by incorporation of additives such as MgCl(2), cysteine, or pancreatin into the overlay medium.