Birth-cohort effects in the association between personality and fertility

The present study investigated whether associations between individuals' personality traits and whether they have children have been modified by birth-cohort effects in the 20th-century United States. Participants were from the Midlife Development in the United States study (n = 6,259) and the Wisconsin Longitudinal Study (n = 3,994) and were born between 1914 and 1974. Data on personality traits of the Five Factor model and fertility history were collected in adulthood. Higher levels of openness to experience in both sexes and higher levels of conscientiousness in women were associated with lower fertility, and these associations strengthened linearly as birth cohorts became younger. In the total sample, high extraversion, low neuroticism, and women's high agreeableness were associated with high fertility rate, but there were no systematic cohort effects. The fertility decisions of people with certain personality traits may be influenced by prevailing societal and cultural circumstances.     

SARA: a cognitive process model to simulate the anchoring effect and hindsight bias

The cognitive process model "SARA" aims to explain the anchoring effect and hindsight bias by making detailed assumptions about the representation and alteration of item-specific knowledge. The model assumes that all processes, namely generating an estimate, encoding new information (i.e., the "anchor"), and reconstructing a previously generated estimate, are based on a probabilistic sampling process. Sampling probes long-term memory in order to retrieve information into working memory. Retrieval depends on the associative strength between this information and the currently active retrieval cues. Encoding the anchor may alter this associative pattern ("selective activation") or the anchor may serve as a retrieval cue, thus directing memory search ("biased reconstruction"). Both processes lead to systematically changed retrieval probabilities, thus causing the anchoring effect or hindsight bias. The model is completely formalised and implemented as a computer program. A series of simulations demonstrates the power of SARA to reproduce empirical findings and to predict new ones.     

Is visual lexical access based on phonological codes? Evidence from a picture-word interference task

The claim that lexical access for visual words is mandatorily mediated by their phonological codes was investigated. Ninety-six subjects performed timed naming responses to pictures while instructed to ignore printed words superimposed on the pictures. Distractor words were either semantically related to the picture label or were homophones of a word semantically related to the picture name. On the basis of the claim that homophones initially activate multiple semantic codes, we hypothesized that the homophone and semantic distractors would yield comparable interference. Picture-word stimulus onset asynchrony (SOA) was varied between subjects as 0 or +100 msec. For an SOA of 0 msec, semantic interference, but no effect from the homophones, was obtained. For an SOA of +100 msec, no effect was obtained in either condition. In combination, these findings indicate a limited role of phonological codes in visual lexical access. It is suggested that the role of phonology in written word identification may vary dependent on procedure and utility to the task.     

Speaking two languages at once: Unconscious native word form access in second language production

Bilingualism research has established language non-selective lexical access in comprehension. However, the evidence for such an effect in production remains sparse and its neural time-course has not yet been investigated. We demonstrate that German-English bilinguals performing a simple picture-naming task exclusively in English spontaneously access the phonological form of –unproduced– German words. Participants were asked to produce English adjective-noun sequences describing the colour and identity of familiar objects presented as line drawings. We associated adjective and picture names such that their onsets phonologically overlapped in English (e.g., green goat), in German through translation (e.g., blue flower – ‘blaue Blume’), or in neither language. As expected, phonological priming in English modulated event-related brain potentials over the frontocentral scalp region from around 440 ms after picture onset. Phonological priming in German was detectable even earlier, from 300 ms, even though German was never produced and in the absence of an interaction between language and phonological repetition priming at any point in time. Overall, these results establish the existence of non-selective access to phonological representations of the two languages in the domain of speech production.     

The neuroscientific study of free will: A diagnosis of the controversy

Benjamin Libet’s work paved the way for the neuroscientific study of free will. Other scientists have praised this research as groundbreaking. In philosophy, the reception has been more negative, often even dismissive. First, I will propose a diagnosis of this striking discrepancy. I will suggest that the experiments seem irrelevant, from the perspective of philosophy, due to the way in which they operationalize free will. In particular, I will argue that this operational definition does not capture free will properly and that it is based on a false dichotomy between internal and external causes. However, I will also suggest that this problem could be overcome, as there are no obvious obstacles to an operationalization of free will that is in accord with the philosophical conception of free will.     

Lactation and stress: protective effects of breast-feeding in humans

Whilst most research on breast-feeding has been designed to assess its importance for infant health or to find a human nutrient replacement for infant formula, the effects of breast-feeding on maternal health have received little scientific attention. In several animal studies lactation has been shown to be associated with a marked blunting of physiological and behavioral responses to physical and psychological stress. However, the literature on the effects of lactation on stress in humans remains limited. This review focuses primarily on recent findings on the effects of breast-feeding on neuroendocrine and behavioral responses to acute stress exposure in lactating women. The available data suggest that breast-feeding suppresses the hypothalamic-pituitary-adrenal (HPA) axis response to physical and psychosocial stress. However, lactation in women, in contrast to lactating rats, does not seem to result in a general restraint of the endocrine stress response during the whole period of lactation. Recent data strongly suggest that the blunted HPA axis response to stress in women seems to be counterbalanced if the acute stressor, at least when of a psychosocial nature, occurs later than 1 h after suckling. Further elucidation of the underlying psychobiological mechanisms involved in suppressed stress responses during lactation will no doubt lead to new insights into improved health sequelae of breast-feeding in women and to a better understanding of the psychobiology of human stress protection in general.     

The effects of aging and dorsal hippocampal lesions: performance on spatial and nonspatial comparable versions of the water maze

Aged intact and young hippocampal-lesioned rats show similar deficits on the spatial water maze. However, this does not necessitate that the source of these deficits in the aged animals is due to hippocampal damage. These water maze deficits may arise from other aging factors such as changes in thermoregulation, muscle fatigue, swim ability, and response to stress. Consequently, it is imperative to examine the performance of aged rats on a comparable nonhippocampal version of this task. Past attempts to develop a hippocampus-independent version of the water maze were confounded because these tasks were easier (i.e., the rats spent much less time swimming in the water) than the spatial versions of the task. The current study examined performance on a hippocampus-independent task comparable in difficulty to the spatial water one. Middle-aged (16-m) and old (25-m) male F344 rats were given sham or dorsal hippocampus lesions and tested on both a spatial and a nonspatial water maze. The middle-aged rats with hippocampal lesions were impaired on the spatial task but not on the nonspatial task. Conversely, aged animals showed a similar impairment on both types of water maze tasks. Additionally, hippocampal lesions exacerbated the age-related impairment on both tasks. These findings indicate that caution must be used when interpreting the results of water maze tasks for aged animals.     

The nature of negative thoughts in depression

We investigated the nature and content of the negative thoughts that accompany depression by examining thoughts about oneself and others during three cognitive tasks: imaging, recall, and inference. Mildly depressed and nondepressed subjects were asked to image, recall, and make inferences about a variety of events while thinking about themselves or another person. The events were sad or happy and either social or nonsocial in nature. The results suggest that the negativity in thought that accompanies depression is restricted to thoughts about oneself and does not extend to thoughts about others. The relation between negative thoughts and the depressive's view of self is discussed. It is proposed that depressives have a negative self-schema that makes the affective nature of their behavior particularly salient.