Alexander E. Wilson

γ-Amino-butyric acid (GABA) receptor subunit and transporter expression in the gonad and liver of the fathead minnow (Pimephales promelas).

γ-Amino-butyric acid (GABA) is the major inhibitory neurotransmitter in the vertebrate central nervous system. GABA receptors and synthesizing enzymes have also been localized to peripheral tissues including the liver, oviduct, uterus and ovary of mammals but the distribution and role of GABA in peripheral tissues of fish has not been fully investigated. The objectives of this study were to (1) determine if mRNA encoding GABA synthesizing enzymes (glutamic acid decarboxylase 65 and 67; gad65 and gad67), GABA transporters, and GABAA receptor subunits are localized to liver and gonad of fathead minnow (Pimephales promelas) (FHM) (2) investigate the effects of GABA on ovarian 17β-estradiol (E2) production, and (3) measure transcript responses in the ovary after in vitro incubation to GABA. Real-time PCR assays were developed for gad65, gad67, vesicular GABA transporter (vgat) and GABA transporter 1 (gat1), and select GABAA receptor subunits (gabra1, gabra5, gabrb1, gabrb2, gabrg1, gabrg2). All transcripts were localized to the brain as expected; however transcripts were also detected in the liver, ovary, and testis of FHMs. In the female liver, gad65 mRNA was significantly higher in expression compared to the male liver. Transcripts for gad67 were the highest in the brain>gonad>liver and in the gonads, gad67 was significantly higher in expression than gad65 mRNA. In the liver and gonad, the relative abundance of the subunits followed a general trend of gabrb1>gabrb2=gabrg1=gabrg2>gabra1=gabra5. To explore the effects of GABA in the ovary, tissue explants from reproductive female FHMs were treated with GABA (10(-10), 10(-8) and 10(-6)M) for 12h. GABA had no significant effect on 17β-estradiol production or on mRNA abundance for genes involved in ovarian steroidogenesis (e.g., 11βhsd, cyp17, cyp19a). There was a significant decrease in estrogen receptor 2a (esr2a) mRNA with 10(-10)M GABA. This study begins to investigate the GABA system in non-neural tissues of teleost fish and addresses the broader topic regarding the peripheral roles of neurotransmitters.

Sex differences in smiling as measured in a picture taking task

Previous research suggests females smile more than males in a picture taking task (Mills, 1984; Morse, 1982; Ragan, 1982). Experiment 1 sought to replicate this effect and, in addition, investigate if the gender of the photographer or instructions to smile would influence smiling in females and males. Subjects were told that their picture would be used in a subsequent facial perception study. Results showed that subjects instructed to smile smiled more than subjects given no instructions. There were no main effects for subjects or photographers gender and no interactions. In Experiment 2, graduating students from the University of New Brunswick, Saint John, completed a questionnaire which assessed how much subjects wanted to smile for their yearbook picture, whether subjects selected a picture of themselves smiling for their yearbook, and how much the photographer encouraged them to smile. Experiment 2 showed that females wished to smile significantly more than males, and females selected a picture of themselves smiling significantly more than males. Males and females did not differ in the reported degree to which the photographer encouraged them to smile. Results from Experiments 1 and 2 suggest that sex differences in smiling as measured in a picture taking task depend critically on the situation in which the picture is taken.

Examination of apparent extent as an explanation of the Poggendorff effect

The explanation of apparent misalignment in the Poggendorff figure, based on underestimation of the intertransversal distance, was investigated in two experiments. In Experiment 1, subjects judged the intertransversal distance in the traditional Poggendorfffigure and two of its variants. The size of the acute angle and the intertransversal distance were manipulated. Half of the subjects made the judgments with the method used by Wilson and Pressey (1976) and the other half made their judgments with the method used by Greist-Bousquet and Schiffman (1981). The results indicated that perceived intertransversal distance was greater with the former method. In Experiment 2, subjects adjusted the transversals to apparent collinearity in the same displays as were used in Experiment 1. The collinearity judgments were transformed to allow comparison with the results of Experiment 1. Comparison of the collinearity judgments with the distance judgments indicated that they did not follow similar trends. For each Poggendorff variant, proportional distance judgments increased as the size of the acute angle increased, and decreased as the intertransversal distance increased. Collinearity judgments did not vary as a function of intertransversal distance. As the size of the acute angle increased, collinearity judgments increased for two of the Poggendorff variants but decreased for the third. It was concluded that the findings did not support the explanation of apparent misalignment based on underestimation of the intertransversal distance.

CONTRAST AND ASSIMILATION IN THE BALDWIN ILLUSION

Four experiments were conducted to investigate the role of “large” squares on the occurrence of assimilation and contrast in the Baldwin illusion. In Exps. 1 and 2, in which subjects reproduced the length of the test line, large squares induced illusions of assimilation. In Exp. 3, reproduction of the entire length of the test line also resulted in illusions of assimilation but bisection of the test line and reproduction of one-half the length of the test line resulted in contrast. Exp. 4 replicated the findings involving judgments of one-half the length of the test line. Over-all, the results indicate that judgments of one-half the length of the test line result in contrast, whereas judgments of the entire extent result in assimilation.

The horizon line, linear perspective, interposition, and background brightness as determinants of the magnitude of the pictorial moon illusion

A total of 110 undergraduate students participated in a series of three experiments that explored the magnitude of the moon illusion in pictures. Experiment 1 examined the role of the number and salience of depth cues and background brightness. Experiment 2 examined the role of the horizon line, linear perspective, interposition, and background brightness. In Experiment 3, comparative distance judgments of the moon as a function of linear perspective, interposition, and the size of the standard moon were obtained. The magnitude of the moon illusion increased as a function of the number and salience of depth cues and changes in background brightness. Experiment 2 failed to support the role of the horizon line in affecting the illusion. Experiment 3 provided additional support for the illusory distance component of the moon illusion.

Effects of method, orientation, and size of angle on the Ponzo illusion.

The Ponzo figure was used to test predictions based upon Presseys 1971 concept of attentive fields. Subjects made judgements using either the method of successive reproduction (n = 18) or the method of reproduction (n = 17). Size of the acute angle between the oblique and test lines (30°, 45°, and 60°) and orientation of test figures (apex pointed up, left, right, and down) were varied. It was predicted with the method of successive reproduction that illusions of shrinkage would occur and that the variable of orientation would not affect size of illusion. With the method of reproduction the prediction was made that illusions of expansion would occur when the apex pointed up and that illusions of shrinkage would occur when the apex pointed down. Analysis showed that with the method of successive reproduction illusions of shrinkage occurred when the apex was pointed either up or down. When the apex pointed either to the right or left nonsignificant illusions were found. With the method of reproduction the classical illusion of expansion occurred when the apex pointed up but changed to one of shrinkage when the apex pointed down. Size of expansion illusion diminished as the acute angle formed between the oblique and standard lines decreased. In general, some of the results were consistent with Presseys concept of attentive fields.

Measuring expectations for participative decision making among graduating nurses.

This paper reports on the initial stage of a research program that examines decisions nurses expect to participate in and the methods by which they expect to participate. This stage of the research focuses on the development of a scale, the Participative Decision Making Scale for Nurses (PDMSN), to measure expectations for participative decision making (PDM) among graduating nurses. It has four subscales that measure expectations for participation in clinical, unit, hospitalwide, and strategic decisions. The PDMSN was administered to two groups of graduating nursing students. Results indicate that the subscales of the PDMSN have high internal consistency; alpha coefficients in Study 1 and Study 2 ranged from .70 to .85 and from .76 to .90, respectively. Patterns of correlations among the subscales and significant correlations with an alternative scale measuring PDM indicate that it is a valid instrument.

Lack of Sex Differences with the Baldwin Illusion

Responses of college students (16 men and 16 women) to the Baldwin illusion showed a significant effect for size of square but not for sex. Findings are consistent with those reported previously by Porac, Coren, Girgus, and Verde for adults and for the oldest group of children tested by Pressey and Wilson.

The effects of arm length, size of angle, and spatial separation on Morinaga’s illusion

The effects of arm length, spatial separation between angles, size of angle, and practice on the degree of misalignment in a modified version of Morinaga’s illusion were assessed. Size of angle was manipulated between subjects (n=15/group), whereas arm length, spatial separation, and practice were varied within subjects. Results showed: (1) that as the length of the arm increased, the degree of illusion decreased; (2) that as spatial separation increased, the degree of illusion increased; and (3) an interaction between size of angle and practice. The results were related to Day et al.’s (1982) assimilation theory of Morinaga’s illusion.

Sex Differences and Spatial Separation in the Poggendorff Illusion1

This study examined the responses of 40 undergraduate women and 40 men to two Poggendorff figures, a traditional figure with the right oblique line omitted and a modified variant with the left vertical line and the right oblique line absent. Participants placed a dot on the right vertical line where the oblique line, if extended, would intersect the right vertical line. The results showed that women displayed larger illusions than men on both figures, consistent with past findings. Finding a sex difference with the modified variant did not support the suggestion that the intersection between the oblique and vertical lines is responsible for such differences. The effects of spatial separation and size of acute angle were similar for both versions of the illusion. The effects of spatial separation were inconsistent with an explanation of the illusion based on depth cues and it was suggested that an explanation of the Poggendorff illusion should focus on processing between the vertical lines.