Sexual differences in memory in shiny cowbirds

Avian brood parasites depend on other species, the hosts, to raise their offspring. During the breeding season, parasitic cowbirds (Molothrus sp.) search for potential host nests to which they return for laying a few days after first locating them. Parasitic cowbirds have a larger hippocampus/telencephalon volume than non-parasitic species; this volume is larger in the sex involved in nest searching (females) and it is also larger in the breeding than in the non-breeding season. In nature, female shiny cowbirds Molothrus bonariensis search for nests without the male’s assistance. Here we test whether, in association with these neuroanatomical and behavioural differences, shiny cowbirds display sexual differences in a memory task in the laboratory. We used a task consisting of finding food whose location was indicated either by the appearance or the location of a covering disk. Females learnt to retrieve food faster than males when food was associated with appearance cues, but we found no sexual differences when food was associated with a specific location. Our results are consistent with the view that parasitism and its neuroanatomical correlates affect performance in memory tasks, but the effects we found were not in the expected direction, emphasising that the nature of avian hippocampal function and its sexual differences are not yet understood. Received: 30 April 1998 / Accepted after revision: 5 September 1998     

Task switches under Go/NoGo conditions and the decomposition of switch costs

Alternating switches between two simple S-R tasks are combined with Go/NoGo tasks. Non-switches after Go trials are assumed to selectively profit from stimulus driven repetition benefits, whereas switches after NoGo trials are assumed to be selectively delayed by stimulus driven negative priming. Intentionally driven reconfiguration costs are assessed by RT differences between switches after Go trials (no negative priming) and non-switches after NoGo trials (no repetition benefits). Experiment 1 indicates that with short preparation time repetition benefits, negative priming costs, and intentional components contribute approximately additively to switch costs. Experiment 2 confirms that the delay of switches after NoGo trials is indeed due to negative priming. Experiments 3 and 4 show that repetition benefits and intentional components of switch costs are properly assessed only if the settings assure that participants reconfigure the required task set in NoGo as well as Go trials.     

Circles of Solicitude and Concern

Abstract

Heidegger distinguishes between concern for things and solicitude for other Dasein. As Dasein is already being‐in‐the‐world and being‐with from the start, there is no need to define what another Dasein is to recognize it. In this paper it is argued that Dasein is thrown into circles of care, where the distinction between solicitude and concern is given. Although this undermines any attempts to regard a comatose patient as non‐Dasein, it raises questions about Dasein’s relations with animals. It is suggested that Dasein’s relations with animals could be captured by inserting another circle, for which the German word versorgen might be suitable.     

Can positive affect induce self-focused attention? Methodological and measurement issues

Some studies find that positive affect can induce self-focused attention, but other studies find no effect. We suggest that the contrary findings result from how self-awareness was measured. One group of participants listened to happy or neutral music; another group imagined and described a happy or neutral event. Two measures of self-focus were then taken. The experiment replicated past findings: Positive affect increased self-focus on a pronoun selection task, but had no effect on a modified private self-consciousness scale. The results were slightly stronger when affect was induced using music. Implications for future research are discussed.     

Poor Readers but Compelled to Read: Stroop Effects in Developmental Dyslexia

We studied a group of 24 children with dyslexia in second to fifth primary school grades by using a discrete-trial computerized version of the Stroop Color-Word Test. Since the classic Stroop effect depends on the interference of reading with color naming, one would expect these children to show no interference or, at least, less interference than normal readers. Children with dyslexia showed, however, a Stroop effect larger than normal readers of the same age. This suggests that reading, although difficult and slow, is an inescapable step that precedes naming both in poor and in normal readers.     

Contextual influences on the internal structure of phonetic categories: A distinction between lexical status and speaking rate

Previous research has shown that phonetic categories have a graded internal structure that is highly dependent on acoustic-phonetic contextual factors, such as speaking rate; these factors alter not only the location of phonetic category boundaries, but also the location of a category’s best exemplars. The purpose of the present investigation, which focused on the voiceless category as specified by voice onset time (VOT), was to determine whether a higher order linguistic contextual factor, lexical status, which is known to alter the location of the voiced—voiceless phonetic category boundary, also alters the location of the best exemplars of the voiceless category. The results indicated that lexical status has a more limited and qualitatively different effect on the category’s best exemplars than does the acousticphonetic factor of speaking rate. This dissociation is discussed in terms of a production-based account in which perceived best exemplars of a category track contextual variation in speech production.     

Cerebellar Substrates for Error Correction in Motor Conditioning

The authors evaluate a mapping of Rescorla and Wagner's (1972) behavioral model of classical conditioning onto the cerebellar substrates for motor reflex learning and illustrate how the limitations of the Rescorla-Wagner model are just as useful as its successes for guiding the development of new psychobiological theories of learning. They postulate that the inhibitory pathway that returns conditioned response information from the cerebellar interpositus nucleus back to the inferior olive is the neural basis for the error correction learning proposed by Rescorla and Wagner (Gluck, Myers, & Thompson, 1994; Thompson, 1986). The authors' cerebellar model expects that behavioral processes described by the Rescorla-Wagner model will be localized within the cerebellum and related brain stem structures, whereas behavioral processes beyond the scope of the Rescorla-Wagner model will depend on extracerebellar structures such as the hippocampus and related cortical regions. Simulations presented here support both implications. Several novel implications of the authors' cerebellar error-correcting model are described including a recent empirical study by Kim, Krupa, and Thompson (1998), who verified that suppressing the putative error correction pathway should interfere with the Kamin (1969) blocking effect, a behavioral manifestation of error correction learning. The authors also discuss the model's implications for understanding the limits of cerebellar contributions to associative learning and how this informs our understanding of hippocampal function in conditioning. This leads to a more integrative view of the neural substrates of conditioning in which the authors' real-time circuit-level model of the cerebellum can be viewed as a generalization of the long-term memory module of Gluck and Myers' (1993) trial-level theory of cerebellar-hippocampal interaction in motor conditioning.     

The Value of Perception

This paper develops a form of transcendental naïve realism. According to naïve realism, veridical perceptual experiences are essentially relational. According to transcendental naïve realism, the naïve realist theory of perception is not just one theory of perception amongst others, to be established as an inference to the best explanation and assessed on the basis of a cost-benefit analysis that weighs performance along a number of different dimensions: for instance, fidelity to appearances, simplicity, systematicity, fit with scientific theories, and so on. Rather, naïve realism enjoys a special status in debates in the philosophy of perception because it represents part of the transcendental project of explaining how it is possible that perceptual experience has the distinctive characteristics it does. One of the potentially most interesting prospects of adopting a transcendental attitude towards naïve realism is that it promises to make the naïve realist theory of perception, in some sense, immune to falsification. This paper develops a modest form of transcendental naïve realism modelled loosely on the account of the reactive attitudes provided by Strawson in ‘Freedom and Resentment’, and suggests one way of understanding the claim that naïve realism is immune to falsification.     

Explanations of the sex‐deviance relationship

This paper examines sex differences in school deviance and compares a cultural/socialization explanation (the machismo thesis) and structural explanations of this differential. In general, the findings show that the sex‐school deviance relationship is completely explained by differences in social controls and pressures which are structured by sex, and that machismo identity may be a mediator of this relationship for aggression but not for general school misconduct. In addition, the findings suggest that sex differences in deviance are enhanced because children tend to be influenced by same‐sexed peers.