Peripheral control of drinking: gastrointestinal filling as a negative feedback signal, a theoretical and experimental analysis.

The studies described here investigated the hypothesis that the osmotic postingestional satiety signal proposed by McCleary operates through a mechanism related to gut filling rather than by osmotically induced shifts of fluid from osmoreceptors in the brain. A control theory model is presented, which was designed to make quantitatively explicit the hypothesis under question. The results showed that when mannitol, which is not absorbed from the intestine, is added to a highly palatable saccharin-glucose mixture, the amount of fluid consumed decreased in inverse proportion to the mannitol concentration. Mannitol was also shown to block fluid absorption from the intestine at a low concentration (approximately .070 M) and at higher concentrations to lead to a net flux of fluid into the intestinal lumen. It was also shown that mannitol in concentrations that reduced the intake of the palatable solution did not induce thirst when the animals were in water balance. It did induce thirst, however, when the animals were tested in a state of negative water balance. The results of these studies, considered as a whole, support the view that McCleary's osmotic postingestional satiety signal acts as an intestinal distention signal rather than by inducing thirst. The model is found to be reasonably accurate as a first approximation, and suggestions are made for improvements.     

Transforming curves into curves with the same shape

Curves are considered to have the same shape when they are related by a similarity transformation of a certain kind. This paper extends earlier work on parallel curves to curves with the same shape. Some examples are given more or less explicitly. A generalization is used to show that the theory is ordinal and to show how the theory may be applied to measure sensation. The problem of actually transforming curves into curves with the same shape is reduced to the problem of rendering another set of curves parallel. Connections with groups and rings are developed to place the work in a familiar context. These connections and the earlier work on parallel curves are used to obtain necessary and sufficient conditions for the existence of transformations, to study the uniqueness of transformations and to show how transformations can be calculated.     

Inheriting the Shadow: Unlived Lives,Unshed Tears

The determination and courage of those whose lives were destroyed by terror, whether the Holocaust or extermination, to move forward in a new life modeled for us, the children, an unspoken mandate to live in the present and to bury the shadows of the past. It has left many of us to face the challenge of finding our center, the anchoring of our being in our lives: personally, professionally, collectively, and culturally. The next generation is not able to mourn lives lost, and being in the present without a past, without links to ethnic cultures or heritage, isolates individuals and affects the collective—indeed, there is no collective except in the communal silences. This article explores the impact of dismembered personal and collective bonds and the need to re-member, resulting in relationships that can move into the future, into the center.     

Spatial Proportional Reasoning Is Associated With Formal Knowledge About Fractions

Proportional reasoning involves thinking about parts and wholes (i.e., about fractional quantities). Yet, research on proportional reasoning and fraction learning has proceeded separately. This study assessed proportional reasoning and formal fraction knowledge in 8- to 10-year-olds. Participants (N = 52) saw combinations of cherry juice and water in displays that highlighted either part–whole or part–part relations. Their task was to indicate on a continuous rating scale how much each mixture would taste of cherries. Ratings suggested the use of a proportional integration rule for both kinds of displays, although more robustly and accurately for part–whole displays. The findings indicate that children may be more likely to scale proportional components when being presented with part–whole as compared with part–part displays. Crucially, ratings for part–whole problems correlated with fraction knowledge, even after controlling for age, suggesting that a sense of spatial proportions is associated with an understanding of fractional quantities.     

Individual differences in visual imagery determine how event information is remembered

Individuals differ in how they mentally imagine past events. When reminiscing about a past experience, some individuals remember the event accompanied by rich visual images, while others will remember it with few of these images. In spite of the implications that these differences in the use of imagery have to the understanding of human memory, few studies have taken them into consideration. We examined how imagery interference affecting event memory retrieval was differently modulated by spatial and object imagery ability. We presented participants with a series of video-clips depicting complex events. Participants subsequently answered true/false questions related to event, spatial, or feature details contained in the videos, while simultaneously viewing stimuli that interfered with visual imagery processes (dynamic visual noise; DVN) or a control grey screen. The impact of DVN on memory accuracy was related to individual differences in spatial imagery ability. Individuals high in spatial imagery were less accurate at recalling details from the videos when simultaneously viewing the DVN stimuli compared to those low in spatial imagery ability. This finding held for questions related to the event and spatial details but not feature details. This study advocates for the inclusion of individual differences when studying memory processes.     

In the Nutshell: Gestational Experience as Liminal Space: Commentary on Thomas Cohen’s Paper “Considering Gestational Life”

Cohen (this issue) raises intriguing questions about the impact of gestational experience but asks his readers to suspend disbelief, as he posits links between this liminal, mysterious, and on some level “unknowable” of times and later phenomenological and relational experience. Using the novel Nutshell, by Ian McEwan, narrated by a fetus who is privy to the portentous events happening outside, as well as inside, his mother’s womb as a frame, I explore questions including how much we can know about fetal subjectivity, how to differentiate the impact of prenatal from postnatal experience, and how that translates to later developmental and clinical realms.     

Spatial anxiety relates to spatial abilities as a function of working memory in children

Spatial ability is a strong predictor of students' pursuit of higher education in science and mathematics. However, very little is known about the affective factors that influence individual differences in spatial ability, particularly at a young age. We examine the role of spatial anxiety in young children's performance on a mental rotation task. We show that even at a young age, children report experiencing feelings of nervousness at the prospect of engaging in spatial activities. Moreover, we show that these feelings are associated with reduced mental rotation ability among students with high but not low working memory (WM). Interestingly, this WM?×?spatial anxiety interaction was only found among girls. We discuss these patterns of results in terms of the problem-solving strategies that boys versus girls use in solving mental rotation problems.     

Opting out or denying discrimination? How the framework of free choice in American society influences perceptions of gender inequality

American women still confront workplace barriers (e.g., bias against mothers, inflexible policies) that hinder their advancement at the upper levels of organizations. However, most Americans fail to recognize that such gender barriers still exist. Focusing on mothers who have left the workforce, we propose that the prevalent American assumption that actions are a product of choice conceals workplace barriers by communicating that opportunities are equal and that behavior is free from contextual influence. Study 1 reveals that stay-at-home mothers who view their own workplace departure as an individual choice experience greater well-being but less often recognize workplace barriers and discrimination as a source of inequality than do mothers who do not view their workplace departure as an individual choice. Study 2 shows that merely exposing participants to a message that frames actions in terms of individual choice increases participants' belief that society provides equal opportunities and that gender discrimination no longer exists. By concealing the barriers that women still face in the workplace, this choice framework may hinder women's long-term advancement in society.