Second-order schedules of token reinforcement with pigeons: effects of fixed- and variable-ratio exchange schedules

Pigeons' key pecks produced food under second-order schedules of token reinforcement, with light-emitting diodes serving as token reinforcers. In Experiment 1, tokens were earned according to a fixed-ratio 50 schedule and were exchanged for food according to either fixed-ratio or variable-ratio exchange schedules, with schedule type varied across conditions. In Experiment 2, schedule type was varied within sessions using a multiple schedule. In one component, tokens were earned according to a fixed-ratio 50 schedule and exchanged according to a variable-ratio schedule. In the other component, tokens were earned according to a variable-ratio 50 schedule and exchanged according to a fixed-ratio schedule. In both experiments, the number of responses per exchange was varied parametrically across conditions, ranging from 50 to 400 responses. Response rates decreased systematically with increases in the fixed-ratio exchange schedules, but were much less affected by changes in the variable-ratio exchange schedules. Response rates were consistently higher under variable-ratio exchange schedules than tinder comparable fixed-ratio exchange schedules, especially at higher exchange ratios. These response-rate differences were due both to greater pre-ratio pausing and to lower local rates tinder the fixed-ratio exchange schedules. Local response rates increased with proximity to food under the higher fixed-ratio exchange schedules, indicative of discriminative control by the tokens.     

Behavioral and pharmacological variables affecting risky choice in rats.

The effects of manipulations of response requirement, intertrial interval (ITI), and psychoactive drugs (ethanol, phencyclidine, and d-amphetamine) on lever choice under concurrent fixed-ratio schedules were investigated in rats. Responding on the "certain' lever produced three 45-mg pellets, whereas responding on the "risky" lever produced either 15 pellets (p = .33) or no pellets (p .67). Rats earned all food during the session, which ended after 12 forced trials and 93 choice trials or 90 min, whichever occurred first. When the response requirement was increased from 1 to 16 and the ITI was 20 s, percentage of risky choice was inversely related to fixed-ratio value. When only a single response was required but the ITI was manipulated between 20 and 120 s (with maximum session duration held constant), percentage of risky choice was directly related to length of the ITI. The effects of the drugs were investigated first at an ITI of 20 s, when risky choice was low for most rats, and then at an ITI of 80 s, when risky choice was higher for most rats. Ethanol usually decreased risky choice. Phencyclidine did not usually affect risky choice when the ITI was 20 s but decreased it in half the rats when the ITI was 80 s. For d-amphetamine, the effects appeared to he related to baseline probability of risky choice; that is, low probabilities were increased and high probabilities were decreased. Although increase in risky choice as a function of the ITI is at variance with previous ITI data, it is consistent with foraging data showing that risk aversion decreases as food availability decreases. The pharmacological manipulations showed that drug effects on risky choice may be influenced by the baseline probability of risky choice, just as drug effects can be a function of baseline response rate.     

The early acquisition of verb meaning in German by normally developing and language impaired children

The research reported here focuses on the early acquisition of event structure in German. Based on longitudinal studies from 5 normally developing (ND) and 6 language-impaired (LI) children, a model of "event structural bootstrapping" is presented that spells out how ND children log into the verb lexicon. They project a target-consistent event tree, depicting the head-of-event of transitions. Young LI children, failing to employ this bootstrapping strategy, resort to radically underspecified event representations. The results from a truth-value judgment experiment with 16 ND and 16 LI children showed that ND children perform correctly on transitional verbs, while LI children perform at chance level on the same tasks. These findings are accounted for by the model of event structural bootstrapping to the extent that LI children lack an explicit representation of the head-of-event.     

God and Contemporary Science: Philip Clayton's Defense of Panentheism

Philip Clayton's God and Contemporary Science is summarized and discussed. Clayton presents a theological reading of biblical texts. In my opinion, science-and-religion studies should deal more substantially with insights of secular studies on the situated character of these texts. Clayton uses the relationship between mind and brain as analogy for the relationship between God and the world. This runs the risk of understanding God as analogous to the mind and hence secondary and emergent relative to the world. Besides, Clayton's arguments for “mental causation” are wanting. But then, why should a defender of panentheism decouple the mental and the material?     

Shaping the Field of Theology and Science: A Critique of Nancey Murphy

Nancey Murphy is a key second-generation figure in the field of religion and science. Through a variety of responsibilities, some of which are reviewed here, she has worked as a discipline builder over the last fifteen years. After trying to convey the general spirit of Murphy's work, the author focuses on five areas where readers might resist her conclusions, including her "postmodern" theory of scientific (and religious) knowledge and truth, her treatment of theology and science as "separate but equal," and her defense of physicalism.     

Wisdom and Life Experience: How Grandfathers Mentor Their Grandchildren

This exploratory study uses qualitative methods to focus on the largely unexamined role of the grandfather and to examine men's experiences as grandfathers. We gathered information through both surveys and individual interviews to explore men's feelings and attitudes toward the grandfather role. Of the 51 grandfathers that completed a survey, 20 participated in interviews. Our examination of the data collected reveals the life lessons men teach their grandchildren. The grandfathers in this study expressed strong desires for purposeful involvement in their grandchildren's lives and indicated desires for transferring values to grandchildren and teaching interpersonal relationships. Through this involvement, they educate through life experiences and serve as mentors for their grandchildren. We suggest that this mentoring role makes a positive contribution to the lives of grandchildren and to the identity of grandfathers.     

Life-Prolonging Killings and their Relevance to Ethics

What makes killing morally wrong? And what makes killing morally worse than letting die? Standard answers to these two questions presuppose that killing someone involves shortening that person's life. Yet, as I argue in the first two sections of this article, this presupposition is false: Life-prolonging killings are conceivable. In the last two sections of the article, I explore the significance of the conceivability of such killings for various discussions of the two questions just mentioned. In particular, I show why the conceivability of life-prolonging killings renders Frances M. Kamm's attempt to provide an answer to the second question problematic.     

Grammer and Social Interaction in Japanese and Anglo-American English: The Display of Context, Social Identity and Social Relation

This paper employs conversation analysis to examine the inter-connection between grammar and displays of contextual understanding, social identity, and social relationships as well as other activities clustering around turn-endings in Japanese talk-in-interaction, while undertaking a restricted comparison with the realisation of similar activities in English. A notable feature of turn-endings in Japanese is the particular salience of grammatical construction on the interactional activities they accomplish. Complete turns which are also syntactically complete are shown to be associated with the explicit display of contextual features, whereas syntactically incomplete turns are designed to circumvent or minimise such displays. The explicit or implicit display of one's social and contextual relationship to the interactional environment is therefore seen to be an integral part of the performance of social actions in Japanese. On the other hand, in English, it is more difficult to establish a clear association between grammar and the inclusion or avoidance of contextual displays.     

How to Identify Negative Actions with Positive Events

It is often assumed that, while ordinary actions are events, ‘negative actions’ (omissions, refrainments, etc.) are absences of events. I claim that a negative action is an ordinary, ‘positive’ event that plays a certain role. I argue that my approach can answer standard objections to the identity of negative actions and positive events.     

Right Action as Virtuous Action

I argue in favour of the central claim of virtue-ethical accounts of right action: that right action is virtuous action. First, I disambiguate this claim and argue for a specific interpretation of it. Second, I provide reasons to prefer target-centred over both agent-centred and motive-centred accounts of virtuous action. Third, I argue that an action is right if, only if, and because it is overall virtuous. Finally, I respond to important arguments to the contrary.