Summation of symbols by pigeons (Columba livia): the importance of number and mass of reward items

In each of 3 experiments, different sets of 4 pigeons (Columba livia) were trained to discriminate between 2 visual symbols that covered wells containing food items that varied in number, mass, or both. In Experiment 1, the symbols were associated with 0, 1, 3, 5, 7, or 9 pieces of grain reward. The pigeons learned to choose the symbol corresponding to the larger reward, and on summation tests, they chose the pair of symbols that summed to the larger total reward. When number of food pellets was varied but mass of reward was held constant in Experiment 2, preference for the larger number symbols failed to appear. When number was held constant and mass was varied in Experiment 3, the pigeons showed a clear preference for the larger mass symbols on single-symbol and summation tests. These findings show that pigeons summate the value of symbols and are more likely to represent symbols by mass of food reward than by number of food items.     

Do People Know How Their Personality Has Changed? Correlates of Perceived and Actual Personality Change in Young Adulthood

Abstract How much do we think our personality changes over time? How well do our perceptions of change correspond with actual personality change? Two hundred and ninety students completed measures of the Big Five personality traits when they first entered college. Four years later, they completed the same measures and rated the degree to which they believed they had changed on each dimension. Participants tended to view themselves as having changed substantially, and perceptions of change showed some correspondence with actual personality change. Perceived and actual change showed theoretically meaningful correlations with a host of variables related to different aspects of college achievement and adjustment.     

Self-affirmation and mortality salience: affirming values reduces worldview defense and death-thought accessibility

To the extent that cultural worldviews provide meaning in the face of existential concerns, specifically the inevitability of death, affirming a valued aspect of one's worldview should render reminders of death less threatening. The authors report two studies in support of this view. In Study 1, mortality salience led to derogation of a worldview violator unless participants had first affirmed an important value. In Study 2, self-affirmation before a reminder of death was associated with reduced accessibility of death-related thoughts a short while thereafter. The authors propose that actively affirming one's worldview alters reactions to reminders of mortality by reducing the accessibility of death-related thoughts, not by boosting self-esteem. These studies attest to the flexible nature of psychological self-defense and to the central role of cultural worldviews in managing death-related concerns.     

Cognitive vulnerability to depression: a taxometric analysis

Although there is increasing support for the hypothesis that negative cognitive styles contribute vulnerability to depression, it remains unclear how best to conceptualize the heterogeneity in cognitive vulnerability to depression. Specifically, does this heterogeneity reflect quantitative or qualitative differences among individuals? The goal of this study was to address this question by examining whether the underlying structure of cognitive vulnerability to depression is best conceptualized as dimensional or categorical. Taxometric analyses provided consistent support for the dimensional nature of negative cognitive styles. It appears, therefore, that cognitive vulnerability to depression is best conceptualized as a dimensional construct, present to a greater or lesser extent in all individuals. Despite this, the strength of the relationship between negative cognitive styles and depressive symptoms does appear to vary as a function of where along the cognitive style continuum one falls.     

Self-experimentation as a source of new ideas: ten examples about sleep, mood, health, and weight

Little is known about how to generate plausible new scientific ideas. So it is noteworthy that 12 years of self-experimentation led to the discovery of several surprising cause-effect relationships and suggested a new theory of weight control, an unusually high rate of new ideas. The cause-effect relationships were: (1) Seeing faces in the morning on television decreased mood in the evening (> 10 hrs later) and improved mood the next day (> 24 hrs later), yet had no detectable effect before that (0-10 hrs later). The effect was strongest if the faces were life-sized and at a conversational distance. Travel across time zones reduced the effect for a few weeks. (2) Standing 8 hours per day reduced early awakening and made sleep more restorative, even though more standing was associated with less sleep. (3) Morning light (1 hr/day) reduced early awakening and made sleep more restorative. (4) Breakfast increased early awakening. (5) Standing and morning light together eliminated colds (upper respiratory tract infections) for more than 5 years. (6) Drinking lots of water, eating low-glycemic-index foods, and eating sushi each caused a modest weight loss. (7) Drinking unflavored fructose water caused a large weight loss that has lasted more than 1 year. While losing weight, hunger was much less than usual. Unflavored sucrose water had a similar effect. The new theory of weight control, which helped discover this effect, assumes that flavors associated with calories raise the body-fat set point: The stronger the association, the greater the increase. Between meals the set point declines. Self-experimentation lasting months or years seems to be a good way to generate plausible new ideas.     

Intellectual performance and ego depletion: role of the self in logical reasoning and other information processing

Some complex thinking requires active guidance by the self, but simpler mental activities do not. Depletion of the self's regulatory resources should therefore impair the former and not the latter. Resource depletion was manipulated by having some participants initially regulate attention (Studies 1 and 3) or emotion (Study 2). As compared with no-regulation participants who did not perform such exercises, depleted participants performed worse at logic and reasoning (Study 1), cognitive extrapolation (Study 2), and a test of thoughtful reading comprehension (Study 3). The same manipulations failed to cause decrements on a test of general knowledge (Study 2) or on memorization and recall of nonsense syllables (Study 3). Successful performance at complex thinking may therefore rely on limited regulatory resources.     

Narrating survival and change in Guatemala and South Africa: the politics of representation and a liberatory community psychology

Peace accords and international interventions have contributed to the suspension of armed conflict and the censuring of repressive regimes in many parts of the world. Some governments and their opposition parties have agreed to the establishment of commissions or other bodies designed to create historical records of the violations of human rights and foster conditions that facilitate reparatory and reconciliatory processes. This paper explores selected roles that community psychologists have played in this process of remembering the past and constructing new identities towards creating a more just future. With reference to two community groups (in Guatemala and South Africa) we show how efforts to speak out about one's own experiences of political and military repression involve complex representational politics that go beyond the simple binary opposition of silencing versus giving voice. The Guatemalan group consisted of Mayan Ixil women who, together with the first author, used participatory action research and the PhotoVoice technique to produce a book about their past and present struggles. The South African group, working within the ambit of the Truth and Reconciliation Commission and in collaboration with the third author and others, explored ways of speaking about their roles in apartheid and post-apartheid society. Although both these initiatives can be seen as moments in on-going struggles to overcome externally-imposed repressive practices that censor the voices of marginalized communities, they also serve to dispel overly romanticized notions of univocal communities now liberated to express themselves in an unmediated and unequivocal fashion. The paper discusses how each group of women instead entered into subtly nuanced relationships with community psychologists involving a continual interplay between the authenticity of their self-representational accounts and the requirements of the discursive technologies into which they were being inducted and the material conditions within their sites of struggle. In both cases the group's agenda also evolved over time, so that what emerged was not so much a particular account of themselves, or even the development of a particular voice for speaking about themselves, but an unfolding process—for the groups and for the community psychologists who accompanied them—of becoming active players in the postmodern, mediated world of self-representational politics and social struggle.     

When parallel processing in visual word recognition is not enough: new evidence from naming

Low-frequency irregular words are named more slowly and are more error prone than low-frequency regular words (the regularity effect). Rastle and Coltheart (1999) reported that this irregularity cost is modulated by the serial position of the irregular grapheme-phoneme correspondence, such that words with early irregularities exhibit a larger cost than words with late ones. They argued that these data implicate rule-based serial processing, and they also reported a successful simulation with a model that has a rule-based serial component—the DRC model of reading aloud (Coltheart, Rastle, Perry, Langdon, & Ziegler, 2001). However, Zorzi (2000) also simulated these data with a model that operates solely in parallel. Furthermore, Kwantes and Mewhort (1999) simulated these data with a serial processing model that has no rules for converting orthography to phonology. The human data reported by Rastle and Coltheart therefore neither require a serial processing account, nor successfully discriminate among a number of computational models of reading aloud. New data are presented wherein an interaction between the effects of regularity and serial position of irregularity is again reported for human readers. The DRC model simulated this interaction; no other implemented computational model does so. The present results are thus consistent with rule-based serial processing in reading aloud.     

Stress within a bicultural context for adolescents of Mexican descent

Folkman and Lazarus's theory of stress and coping was used to develop a measure assessing the perceived stress within a bicultural context. Middle school students of Mexican descent (N = 881) reported their perceived stress from intergenerational acculturation gaps, within-group discrimination, out-group discrimination, and monolingual stress. Although immigrant youths reported more total number of stressors, U.S.-born youths reported more stress from needing better Spanish and impact of parents' culture. Immigrant youths reported more stress from needing better English in school. Higher stress was associated with more depressive symptoms for both U.S.-born and immigrant youths. Although this study has identified some elements of stress, it has not identified positive coping mechanisms of the bicultural context for Latino youths.     

A longitudinal study of personality change in young adulthood

The present research examined personality continuity and change in a sample of young men and women assessed at the beginning and end of college. Two-hundred seventy students completed measures of the Big Five personality traits when they first entered college and then 4 years later. Analyses indicate small- to medium-sized normative (i.e., mean-level) changes, large rank-order stability correlations, high levels of stability in personality structure, and moderate levels of ipsative (i.e. profile) stability. Overall, the findings are consistent with the perspective that personality traits exhibit considerable continuity over time, yet can change in systematic ways.