The experimental study of itch was reviewed, and an experiment performed to test the effects of ipsilateral and contralateral counterirritation distal to the itching wrist. Each of the 18 subjects served in all experimental conditions, receiving cowage as the itch stimulus and a placebo. Counterirritation consisted of a 10-sec immersion of the fingers into a 2° C water bath. Lateral differences both in response to cowage and to counterirritation were obtained. In general, counterirritation reduced itch significantly more than the control procedure during the treatmenj period and the first three intervals following treatment. The results of the present experiment suggest a central mechanism attenuating the sensation of itch.

Two experiments were conducted to determine the effects of distinctive features on recognition of incomplete pictures. Two sets of fragmented picture stimuli were designed: Set A preserved 75% and Set B preserved 25% of the distinctive features of the objects pictured. Within each set of stimuli, a complete (C), an intermediate (I), and a most incomplete (MI) representation of the objects was constructed. In the first experiment, 60 subjects of three different age groups were tested on the MI representations of either Set A or Set B. Results indicate significant differences in the age groups and in stimulus sets. In the second experiment, 36 children were trained on either the C or the I Set A or the I Set B representations. After a day's delay, the children were tested on Set A or Set B MI representations of the objects and to novel representations. Results showed significant differences among training conditions and in the test of the stimulus sets. The concepts of filtering and abstraction of distinctive features as discussed in 1969 by Gibson are mainly used in interpreting the results of the experiments.

Cold-water stimulation was used to measure pain in 41 female subjects. Prior to each experimental trial, subjects placed their hands in an adapting bath of 32° C. for 2 min.; their judgments of this water temperature as rated on a 200-point scale were recorded every 30 sec. The subjects then immediately placed one hand into the cold-water bath of 2.0° C.; measures of pain threshold and tolerance were recorded. Ten trials per subject were administered-five for the left and five for the right hand. Pain threshold and tolerance were greater for the right hand than for the left, regardless of the hand preference of the subjects. Threshold values correlated positively with values of tolerance.

Minimum tone levels (.125-32.0 ke.) that produced immobility responses (IRs) in 6 guinea pigs were near the thresholds of audibility and 60-90 db. below those for pinna reflexes. The guinea pig's audibility curve is near man's to about 10 kc. but extends to 32 or 50 kc. Durations of IRs to tone initially ranged from 2 sec. to 36 min. and were longer for high than low SPLs; responses ceased in 10-13 trials. Generalization gradients over frequency and intensity showed selective habituation. IRs were evidently influenced by motivational variables and by stimulus novelty.

Cold water stimulation wag used to measure pain in the hands and feet of 10 siriistral and 10 dextral subjects. After an adaptation trial the subject then placed her foot (hand) in water of 2° C.; threshold and tolerance levels were then recorded. A total of 20 trials, 5 with each hand and foot, were administered with each subject. Greater sensitivity and pain tolerance was obtained in the left hand and foot of both sinistral and dextral subjects, and sinistral subjects were less sensitive than dextral subjects. Results provide more support for an interpretation involving bilateral assymmetry of the brain than one involving hand and foot calluses.