EXPERIMENTER CALCULATION ERRORS: A POTENTIAL FACTOR AFFECTING INTERPRETATION OF RESULTS1

Following a study of socially withdrawn children, it was noted that checks of experimenter calculations indicated discrepancies. The present study investigated the magnitude and direction of experimenter errors in data computations. Two full-time research assistants, who served as experimenters, processed the behavioral observation data. These experimenters were referred to as the subjects in this study. Standard data values, against which the subjects' computations were compared, were established by two other research assistants and a computer staff. The results indicated that experimenters' original data values disagreed with the standard data values. The daily errors showed considerable variability for both experimenters. The specific factors accounting for this variability could not be identified, although frequency of experimenter responses required to obtain rate and duration data, time spent calculating, and complexity of task were suggested as possible contributing variables. While disagreements occurred across all experimental days, the magnitude of differences was generally small. An examination of direction of differences in both experimenters' data showed no systematic trends in favor of the experimental hypothesis. Rather, there appeared to be a trend in the other direction. This study suggests that the same research decisions would have been made during the original investigation using either set of data.     

Perspective role-taking in young children

Children between the ages of 4 and 7 years were asked to select a photograph depicting the visual perspective of a puppet which was placed at various locations around a dollhouse in a modified version of Piaget and Inhelder's three-mountain task. A shielded condition was used for half of the children. Three types of errors were examined in relation to the shield condition, age, and type of vantage point (views from the corners and from the sides). Shielding of the stimulus array reduced egocentric errors among 4-year-olds, producing a pattern of responses more typical of that observed among older children. Increasing specificity in perspective role-taking with age was indicated by changes in error patterns. Finally, the task was more difficult on trials with corner views, particularly when the child's own view included some of the cues present in the puppet's perspective.     

On spurious allusions

The criticisms of Walker’ theory by MacLeod, Virsu, and Carpenter are shown to stem from a too simple reading of the text of the theory, a failure to investigate fully the references cited to support their position, and an effort to bolster the theory of lateral inhibition in orientation detectors. The criticisms are shown to misrepresent the experimental data of various reports. Walker’s physiological premises are shown to be sound, and the cases of “contrary evidence” are shown infact to be in agreement with the theory. Lateral inhibition in orientation detectors as an explanation of optical illusions is shown to fail completely to agree with experimental results.     

The octopus in the laboratory. Handling,maintenance, training

Octopus maya lives well for long periods in a small tank containing a plastic house in which it can be carried without disturbance to and from an experimental situation. Data are reported on the growth of animals kept under these conditions as a function of feeding schedule and on their food intake as a function of deprivation. Some animals were trained in a runway with food as reward, and others were trained in a simple maze with return to sea water as reward.     

An Examination of Gender Differences in Mexican-American Attitudes Toward Family and Career Roles

This study examined attitudes of 76Mexican-American females and 62 Mexican-American malestoward the role of the female in the workplace andtoward child care responsibility of working parents.Controlling for age, marital status, number of children,and acculturation, males were significantly more likelyto hold traditional views of the role of females in theworkplace than were females. Additionally, controlling for the same variables, males weresignificantly more likely than females to havetraditional views toward parental responsibility forchild care. Future research needs arediscussed.     

The Role of Body Weight,Waist-to-Hip Ratio,and Breast Size in Judgments of Female Attractiveness

It was demonstrated by Singh and Young (1995)that morphological features such as overall body fatdistribution measured by waist-to-hip ratio (WHR) andbreast size, influence judgments of femaleattractiveness, age, and desirability for relationships. Thepresent study was a replication and extension of thatresearch, using both male and female participants. Theresults supported the general findings of the original study, and as predicted, the effect of breastsize on attractiveness judgments depended on overallbody fat and WHR. The significance of interactionswithin the different morphological features whichdetermine female attractiveness were noted. Overall,there were surprisingly few sex differences. Results arediscussed in terms of the socio-biological theoriescurrently popular in the literature.     

Effects of variable-interval value and amount of training on stimulus generalization.

In Experiment 1 pigeons pecked a key that was illuminated with a 501-nm light and obtained food by doing so according to a variable-interval (VI) schedule of reinforcement, the mean value of which differed across groups: either 30 s, 120 s, or 240 s. The pigeons in all three groups were trained for 10 50-min sessions. Generalization testing was conducted in extinction with different wavelengths of light. Absolute and relative generalization gradients were similar in shape for the three groups. Experiment 2 was a systematic replication of Experiment 1 using line orientation as the stimulus dimension and a mean VI value of either 30 s or 240 s. Again, gradients of generalization were similar for the two groups. In Experiment 3 pigeons pecked a key that was illuminated with a 501-nm light and obtained food reinforcers according to either a VI 30-s or a 240-s schedule. Training continued until response rates stabilized (> 30 sessions). For subjects trained with the 30-s schedule, generalization gradients were virtually identical regardless of whether training was for 10 sessions (Experiment 1) or until response rates stabilized. For subjects trained with the VI 240-s schedule, absolute generalization gradients for subjects trained to stability were displaced upward relative to gradients for subjects trained for only 10 sessions (Experiment 1), and relative generalization gradients were slightly flatter. These results indicate that the shape of a generalization gradient does not necessarily depend on the rate of reinforcement during 10-session single-stimulus training but that the effects of prolonged training on stimulus generalization may be schedule dependent.