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The experiment evaluated the influence of visual and auditory action-information feedback on stylus-maze learning during acquisition, when such feedback was presented concurrently with the response and on transfer trials where such feedback was withdrawn. Terminal-information feedback designating serial error, and summary feedback, identifying time and error scores, were provided under both conditions. 40 apparatus-naive undergraduates were assigned to one of two conditions of action-information feedback. Both groups improved in speed and accuracy of performance during acquisition with superior results under visual condition. The reverse situation was evidenced during withdrawal of information feedback when the auditory group was relatively less affected by the removal of guidance than the visual group. The results are discussed in relation to the maze-task requirements and in terms of hypothesized performance-learning variables of action-information feedback.

Retention performance in independent groups of rats was examined at various intervals following one-trial appetitive maze training in which water reinforcement was available in the goal box. A control procedure minimized deprivation differences between the various groups. Results of this first experiment indicated multiple retention deficits similar to those previously found only for avoidance behaviors. Retention was significantly better in the 12 hr, 24 hr, and 36 hr groups than in the 6 hr, 18 hr, and 30 hr groups. Performance by the 0.25 hr and 1 hr groups was intermediate. A second experiment was designed to determine whether non-reinforced behavior in the same apparatus would also fluctuate periodically. The performance of rats in this experiment did not parallel the rhythmic pattern of the rats in Expt I. These periodic performance fluctuations in Expt I are explained in terms of “state-dependent” retrieval based upon some internal biological rhythmic process, in which footshock induced factors apparently play a minimal role.

Rat pups injected on Postnatal Days 2-4 with subcutaneous doses of triiodothyronine (T3 ) up to 4 micrograms/g showed substantial accelerations in the maturation of swimming behavior, righting reflexes, and eye opening which were greater than the accelerations produced by neonatal thyroxine (T4 ) in a previous study. They also showed significantly higher activity in stabilimeter cages on Postnatal Day 13 but not an expected earlier peak than normal rats in the ontogeny-of-arousal functions obtained in stabilimeter testing. As adults, the T3 -treated rats displayed large maze learning deficits which were comparable in size to those produced by fairly severe thyroid deficiency in the perinatal period.

Extract: Rats whose mothers received hydroxyurea (HU, 1 or 2 g/kg) at 14 days of gestation had a 30% deficit in both brain and body weight at birth, when compared with controls. Number of brain cells at birth (mainly neurons) was reduced by 33–34%. A severe reduction in postnatal whole brain growth (31–33% in adulthood) was observed, but the cerebellum was relatively spared. In the Hebb-Williams maze text in adulthood HU animals made 28% more errors than controls over 12 problems. The differences were much more marked on certain problems and for HU animals with particularly small brains. In a T-maze spatial discrimination test in adulthood HU rats learned the initial response normally but, when required to reverse this response, showed a significant tendency to make more perseverative errors than controls. Speculation: Rats exposed to an inhibitor of cell division at the beginning of the major period of brain neurogenesis showed deficits in learning ability in adulthood. The large number of mentally retarded human children whose handicap is without known etiology may have suffered a similar early loss of neurons, and if so, this preparation could provide a useful animal model.

In a recent report by Furchtgott, et al. ( 1961 ), exploratory behavior in an open field situation was found to decrease with increasing age. These investigators used naive animals at each age of testing and terminated their study at 390 days of age. The present investigation confirms some of the findings of the above mentioned report, utilizing a different experimental design with repeated testing of the same animals to demonstrate chat the age factor is more important than the "novelty" of the experience. Additional data on animals tested at an older age and on sex differences are presented for the open field measures. METHOD Sabjects.-Ss were 28 albino rats of the Sprague-Dawley strain purchased from the Holtzman Co. The original group of 12 females and 16 males was reduced by death, disease, and other attrition factors to 12 females and 8 males on whom open field measures at each age were available. Animals were maintained on Purina laboratory chow and water ad libitam throughout their lifetime except for 3 weeks as 100 days of age during which time they were on a 23-hr. water deprivation schedule. Animals arrived in the laboratory at 45 days of age and were routinely weighed and handled at least once a week. At 100 days of age and after the first open field test, they were rested in a maze learning situation. At 360 days of age, attempts were made at macing the animals. Aside from these manipulations, each S received little or no handling and lived his routine life with a same sex cagemate. Apparatzrs and procedure.-The open field test used and the procedure employed was similar to that described by Stern (1956). T he apparatus was 3 by 5 ft., painted black and divided into 15 1-ft. squares marked by a chalk line. Lighting was uniform from overhead and the animals were observed through a one-way vision window. Animals were run for 5 consecutive daily 2-min. trials when 90, 180, 360, and 540 days of age. The number of squares traversed and the number of "emotional" activities such as defecating, urinating, edging, face washing, rearing, crouching, etc. were recorded.

Equal numbers of male and female rats of the King-Holtzman hybrid breed, divided into two age groups (group A1: 21–30 days old and group A2: 90–100 days old), were exposed to two levels of noise: N0 = 30 db and N1 = 90 db, (ref. 0.002µbar), and three levels of direct electric field intensities: E0 = electric field strength of zero; E1 = 1,600 v/m; and E2 = 16,000 v/m. Time and error scores of 240 rats running a modified Lashley left-right maze with an escape-from-water motive served as criteria. A randomized complete blocks design with replications (2 × 3 × 2 × 2 × 10) was selected for treatment by analysis of variance. The results indicate that (a) adult rats pre-exposed to electric fields showed significantly lower error scores than young rats, regardless of sex or the noise condition; (b) after exposure to electric fields all rats swam faster than their controls; (c) after exposure to noise females showed significantly higher time scores than males under the same conditions, regardless of age; and (d) when subjected to the combined effect of electric fields and noise males showed significantly lower time scores than females under the same conditions, regardless of age.

Zajonc's proposal that the presence of others facilitates emission of dominant responses was examined in a coaction setting with human maze learning. On a maze where dominant responses were likely to be correct, coacting subjects made fewer errors than those working alone. On a maze where dominant responses were likely to be incorrect, subjects performing alone made fewer errors than those coacting. Investigation of task performance at different stages in learning showed that a change in the rate of learning corresponded to a change in the dominant response from incorrect to correct. It was concluded that the presence of others has a facilitative effect on the dominant response, hindering learning when the dominant response is incorrect and helping learning when the dominant response is correct. Coaction effects were extremely pronounced in females but almost nonexistent in males.

The experiment was designed to test effects of experimentally induced hyperlysinemia on maze learning ability in the mouse. Six% L-lysine was placed in the drinking water during gestation, and/or during nursing and/or during postweaning in a factorial combination. The young were tested at 40 days of age in a water-escape T maze. A week later all animals were retested for retention. Findings revealed that overloads of lysine resulted in temporary impairment, but permanent impairment occurred only if excess lysine was administered during gestation. Biochemical analysis revealed a sharp decrease in urea nitrogen in the urine, and a blood ammonia and lysine increase.

(1956). Sensory Contributions to Human Maze Learning: A Comparison of Matched Blind, Deaf, and Normals. The Journal of General Psychology: Vol. 54, No. 1, pp. 81-93.

1. The effect of insulin injections, sufficient in strength to cause convulsive seizures and/or lethargy, has been systematically studied in relation to various aspects of the learning process. 2. For maze learning the following statements have been experimentally verified and established: (a) Insulin has a greater disintegrative effect on the learning of a habit which has been less well fixed than on a habit of greater fixation. (b) Insulin has a greater disintegrative effect on the learning of a longer and more difficult maze than on a shorter and easier maze, when both are learned to the same norm. (c) Insulin has a disintegrating effect on the initial acquisition of a maze habit when compared to the acquisition of the same habit under normal conditions. (d) The effects described in the above statement are definitely the result of insulin injection. Comparison of the use of insulin and saline solution proves insulin to have a disintegrative effect which is lacking in the saline situation. Our work has ...

Strychnine sulphate injected into 2 groups of rats 24-hours and 3-days, respectively, prior to maze-learning improved performance. This suggests that following an injection the drug, or some effect of the drug on the body, endures for a relatively long period. Current research on memory is criticized.

Animals ( N = 24) of the Maudsley Reactive and Non-Reactive strains of rats were trained in the Hebb-Williams maze. Immediately after each daily trial the experimental subjects were injected with 0·8 mg/kg of nicotine; a control group was administered distilled water. The experimental group and the Reactive strain performed significantly better than their controls; these results are seen as support for the neural consolidation hypothesis.

Moderate hypochermia, or a slight reduction of body temperature from a point within the normal limits of the range of body temperature variability, has been given some attention in the clinical literature, This attention has been focused primarily on functional somatic changes or variations induced by the hypothermia. Observations dealing with behavioral functions have come mainly from clinical studies in which the behavioral data were secondary to the application of hypothermia in medical or surgical procedures (Fay, 1940; Allen, et al., 1960). In these observations there have been reports of a behavioral deficit in cognitive functioning. Previous experimental studies (Essman, Sudak, & Blumstein, 1961; Essman 8i Sudak, 1962; Sudak & Essman, 1962?) have suggested impaired maze acquisition when body temperature was lowered (2OC co 5OC), a cemperature-dependent variable related to learning, and no effect of such a moderate degree of temperature reduction upon performance. The precise limits of temperature variability in the mouse (Mus masctdlar) have not been clearly defined. In one instance (Speccor, 1956, p. 343) 35.2'C to 37.9'C has been specified. In another instance (Usinger, 1957) the range is given as 34'C to 39°C for ambient temperatures of 20°C to 35°C. In our own experience we have found that in individual measurements made on SwissWebster mice variation of deep colonic temperature occurs from 36'C to 39OC at an ambient temperature of 25°C & l.O°C. The question arising out of previous work has been what degree of reduction from the upper normochermic range must a temperature be to influence the acquisition of a simple maze response. This implies the hypothesis chat temperature reduction per se rather than a temperarure difference within the norrnochermic range is [he critical variable as far as the acquisition process is concerned. Furthermore, it is hypothesized that moderate sustained hypothermia will interfere with acquisirion while moderate temporary hypothermia will have no effect. This hypothesis is based upon the premise that a sustained reduction of body temperature during acquisition experience does not allow for neural consolidacion~'

No significant correlation was found between avoidance conditioning and maze learning in a sample of 52 male albino rats of an heterogeneous strain of the Wistar type. Psychopharmacological implications are discussed on the basis of large independence of the performances in the two tasks.

Mice injected with 280 mg/kg of highly purified yeast RNA learned to avoid shock by choosing a white rather than a black door in a Y-maze at the same rate as saline-injected controls. The generality and interpretation of reports on enhancement of acquisition following RNA injection is questioned.