acase@tulane.edu

acase@tulane.edu

The effects of prenatal stress and maternal age on developmental indices and sexual differentiation in male and female rats were investigated. Pregnant females exposed to the stress of restraint and high intensity illumination during Days 14-21 of gestation produced fewer live pups and exhibited shorter gestation lengths than nonstressed control females. Male offspring of stressed mothers had lower body weights, lighter testes and delayed testes descent as compared to the male offspring of nonstressed mothers. These effects were greatest in male offspring of younger stressed mothers. Copulatory behaviors were also impaired in prenatally stressed males. Prenatally stressed males exhibited fewer mounts and ejaculations and longer latencies to intromission and ejaculation than nonstressed males. Prenatally stressed female offspring had shortened anogenital distance, delayed eye opening and lower body weights than nonstressed females. The effect of stress on eye opening and body weight was greatest in the offspring of younger mothers. Anogenital distance, however, was altered more in offspring of older stressed mothers. Regardless of the age of the mother, prenatally stressed offspring exhibited irregularities in estrus cycling and alterations in proceptive behaviors. Females injected on Day 3 with 3.5 (mu)g Testosterone Propionate (TP) had earlier vaginal opening, increased incidence of cystic ovaries and became anovulatory at an earlier age than oil-injected females. More TP-injected females of stressed mothers had cystic ovaries and were sterile at an earlier age than any other group. TP-injected females exhibited reduced levels of proceptive behavior which suggests similar effects of prenatal stress and neonatal androgenization / acase@tulane.edu

acase@tulane.edu

acase@tulane.edu

Learning procedures and type of tasks have become useful variables to explain the amount and quality of retention and transfer in problem solving. However, the results are conflicting and often insignificant due to limitations in the design and analysis. The purpose of the present experiment is to examine the effectiveness of several learning methods on transfer and to investigate the possible interaction between learning methods and type of task. A 2 x 4 factorial design involving two different types of tasks (anagrams and Luchins' water-jar problems) and four treatments {both rules and examples given (Condition RE); rules given but without examples (Condition RE); examples only without rules (Condition RE); and neither rules nor examples (Condition RE)} were used. As a response measure we used the percentage of problems solved successfully on posttest and transfer. The results show (1) highly significant and consistent interactions of Tasks x Treatments and Tests x Treatments; (2) powerful influence on both retention (positive efforts) and transfer (negative effects) by the rule factor; (3) overall, better learning resulted from the discovery method. Functional fixedness was hypothesized and confirmed, particularly with anagrams. Several factors responsible for the superiority of discovery over rule learning are presented as well as some implications for developing a more rational technique of instruction / acase@tulane.edu

acase@tulane.edu

Seven subjects participated in a dichotic listening task and judged in which ear the leading stimulus was presented. The stimuli consisted of six speaker-produced stop consonant-vowels, /ba/, /da/, /ga/, /pa/, /ta/, and /ka/ which were digitally edited to durations of 40, 60, 90, and 180 msec. The experiment was blocked by stimulus duration. At each condition of duration, listeners judged the temporal order of stimuli separated by 4, 8, 16, 32, or 64 msec asynchrony. There were significant main effects of both asynchrony and stimulus duration. Sensitivity increased with longer asynchronies and also for longer durations. Thresholds, between 16 and 32 msec asynchrony, approximated those reported by others. A further comparison of intensity levels, 66 dB SPL and 100 dB SPL, for the 40 msec duration condition proved non-significant. The results are compared to earlier investigations which reported increases in sensitivity for shorter duration stimuli, but which, in all cases, employed monotonically presented sinusoids. The results of the present study suggest that stimulus duration affects temporal order judgment at central as well as peripheral levels of processing / acase@tulane.edu

acase@tulane.edu

acase@tulane.edu