Irrelevant incentive learning during training on ratio and interval schedules

Two experiments investigated the effect of a motivationally-induced change in the value of the training reinforcer on instrumental performance. Initially, thirsty rats were trained to lever press for either a sodium or a potassium solution. Responding in an extinction test was then measured following the induction of sodium appetite. In Experiment I sodium-trained rats responded faster in a test given one day following the end of instrumental training. Furthermore, the relative size of this irrelevant incentive effect did not depend upon whether a ratio or interval schedule was employed during training. Delaying the test for eight days following the end of training abolished the difference between the test performance of sodium- and potassium-trained animals. Experiment II provided a further study of the effect of the training schedule when the introduction of the sodium reinforcer was delayed until responding was well established. Again the relative size of the difference between the performance of sodium- and potassium-trained animals was comparable following training on ratio and interval schedules. The insensitivity of this irrelevant incentive effect to the training contingency is in marked contrast to previous failures to detect an effect of reinforcer revaluation brought about by aversion conditioning following training on an interval schedule (Dickinson, Nicholas and Adams, 1983).     

Distractor ratio and grouping processes in visual conjunction search.

According to feature integration theory, conjunction search is conducted via a serial self-terminating search. However, effects attributed to search processes operating on the entire display may actually reflect search restricted to elements defined by a single feature. In experiment 1 this question is addressed in a reaction-time (RT) paradigm by varying distractor ratios within an array of fixed size. For trials in which the target was present in the array, RT functions were roughly symmetric, the shortest RTs being for extreme distractor ratios, and the longest RTs being for arrays in which there were an equal number of each distractor type. This result is superficially consistent with Zohary and Hochstein's interpretation that subjects search for only one distractor type and are able to switch search strategy from trial to trial. However, negative-trial data from experiment 1 case doubt on this interpretation. In experiment 2 the possible role of 'pop out' and of distractor grouping in visual conjunction search is investigated. Results of experiment 2 suggest that grouping may play a more important role than does distractor ratio, and point to the importance of the spatial layout of the target and of the distractor elements in visual conjunction search. Results of experiment 2 also provide clear evidence that groups of spatially adjacent homogeneous elements may be processed as a unit.     

Disjunctivism and skepticism

Disjunctivism is the view that perceptual experience is either constituted by fact in the world or mere appearance. This view is said to be able to guarantee our cognitive contact with the world, and thus remove a crucial “prop” upon which skepticism depends. This paper has two aims. First, it aims to show that disjunctivism is a solution to Cartesian skepticism. Cartesian skepticism is an epistemological thesis, not an ontological one. Therefore, if there is an external world, we may well undergo a veridical experience, and thus we can take advantage of disjunctivism to adopt an anti-evidential-skepticism strategy to counter Cartesian skepticism. Second, this paper argues that disjunctivism fails to solve Pyrrhonian skepticism. To counter Pyrrhonian skepticism, one has to give reasons both for his belief and for his believing. But disjunctivism can only account the former, that is, the reason for the content of perceptual belief. Given that one’s experience in good case and bad case is subjectively indistinguishable, one cannot just use his experience to justify his believing. This shows that disjunctivism cannot meet the requirement to provide an adequate account for reflective knowledge.     

Heterophenomenology and phenomenological skepticism

This paper is an attempt to clarify and assess Dennett’s opinion about the relevance of the phenomenological tradition to contemporary cognitive science, focussing on the very idea of a phenomenological investigation. Dennett can be credited with four major claims on this topic: (1) Two kinds of phenomenological investigations must be carefully distinguished: autophenomenology and heterophenomenology; (2) autophenomenology is wrong, because it fails to overcome what might be called the problem of phenomenological scepticism; (3) the phenomenological tradition mainly derived from Husserl is based on an autophenomenological conception of phenomenology, and, consequently, can be of no help to contemporary cognitive science; (4) however, heterophenomenology is indispensable for obtaining an adequate theory of consciousness. In response to Dennett’s analysis, the paper develops two main counterclaims: (1) Although the traditional conception of phenomenology does indeed fit Dennett’s notion of autophenomenology, his sceptical arguments fail to rule out at least the possibility of a modified version of this traditional conception, such as the one defended in Roy et al. (Naturalizing Phenomenology, 1999); (2) the distinction between autophenomenology and heterophenomenology is at any rate misconceived, because, upon closer analysis, heterophenomenology proves to include the essential characteristics of autophenomenology.     

Skeptical hypotheses and moral skepticism

Moral skeptics maintain that we do not have moral knowledge. Traditionally they haven't argued via skeptical hypotheses like those provided by perceptual skeptics about the external world, such as Descartes' deceiving demon. But some believe this can be done by appealing to hypotheses like moral nihilism. Moreover, some claim that skeptical hypotheses have special force in the moral case. But I argue that skeptics have failed to specify an adequate skeptical scenario, which reveals a general lesson: such arguments are not a promising avenue for moral skeptics to take. They're ultimately weaker when applied to morality compared to perception.     

A-symmetric confirmation and anthropic skepticism

Synthese - In recent years, anthropic reasoning has been used to justify a number of controversial skeptical hypotheses (both scientific and philosophical). In this paper, we consider two prominent...     

Discursive justification and skepticism

In this paper, I consider how a general epistemic norm of action that I have proposed in earlier work should be specified in order to govern certain types of acts: assertive speech acts. More specifically, I argue that the epistemic norm of assertion is structurally similar to the epistemic norm of action. First, I argue that the notion of warrant operative in the epistemic norm of a central type of assertion is an internalist one that I call ??discursive justification.?? This type of warrant is internalist insofar as it requires that the agent is capable of articulating reasons for her belief. The idea, roughly, is that when one asserts that p, one is supposed to be in a position to give reasons for believing that p. Bonjour??s reliable clairvoyant Norman, for example, is not in an epistemic position to make assertions regarding the president??s whereabouts??even if Norman knows the president??s whereabouts. In conclusion, I briefly consider whether a type of skeptical argument??often labeled Agrippa??s Trilemma??is motivated, at least in part, by the fact that responses to it violate the relevant epistemic norm of assertion.     

Modal skepticism and counterfactual knowledge

Timothy Williamson has recently proposed to undermine modal skepticism by appealing to the reducibility of modal to counterfactual logic (Reducibility). Central to Williamson’s strategy is the claim that use of the same non-deductive mode of inference (counterfactual development, or CD) whereby we typically arrive at knowledge of counterfactuals suffices for arriving at knowledge of metaphysical necessity via Reducibility. Granting Reducibility, I ask whether the use of CD plays any essential role in a Reducibility-based reply to two kinds of modal skepticism. I argue that its use is entirely dispensable, and that Reducibility makes available replies to modal skeptics which show certain propositions to be metaphysically necessary by deductive arguments from premises the modal skeptic accepts can be known.     

Irrelevant Alternatives and Frankfurt Counterfactuals

In rejecting the Principle of AlternatePossibilities (PAP), Harry Frankfurt makes useof a special sort of counterfactual of thefollowing form: ``he wouldn't have doneotherwise even if he could have'. Recently,other philosophers (e.g., Susan Hurley (1999,2003) and Michael Zimmerman (2002)) haveappealed to a special class of counterfactualsof this same general form in defending thecompatibility of determinism andresponsibility. In particular, they claim thatit can be true of agents that even if they aredetermined, and so cannot do otherwise, theywouldn't have done otherwise even if they couldhave. Using as a central case an argument ofSusan Hurley's, I point out that thecounterfactuals in question are both``interlegal' and ``indeterministic', and I raisedoubts about whether this special class ofcounterfactuals have clear truth conditions. Finally I suggest that acknowledging thesepoints leads to an appreciation of the realstrength of Frankfurt-style examples.     

Theory skepticism and moral dilemmas

Moral-theory skepticism is not an option in any sort of thinking that could actually be used in resolving dilemmas in applied ethics, since its characteristic doctrines entail positions that in practice often will lead to a kind of paralysis in in moral reasoning, where persons faced with having to decide what to do in particularly difficulty cases are unable to rule out the most implausible conclusions. Moral-theory skepticism thus makes it difficult to formulate decision-making procedures that will provide guidance in action, and, so, seems not to succeed as a fully coherent account of moral reasoning.     

Irrelevant speech effects and statistical learning

Immediate serial recall of visually presented verbal stimuli is impaired by the presence of irrelevant auditory background speech, the so-called irrelevant speech effect. Two of the three main accounts of this effect place restrictions on when it will be observed, limiting its occurrence either to items processed by the phonological loop (the phonological loop hypothesis) or to items that are not too dissimilar from the irrelevant speech (the feature model). A third, the object-oriented episodic record (O-OER) model, requires only that the memory task involves seriation. The present studies test these three accounts by examining whether irrelevant auditory speech will interfere with a task that does not involve the phonological loop, does not use stimuli that are compatible with those to be remembered, but does require seriation. Two experiments found that irrelevant speech led to lower levels of performance in a visual statistical learning task, offering more support for the O-OER model and posing a challenge for the other two accounts.     

Irrelevant speech effects and sequence learning

The irrelevant speech effect is the finding that performance on serial recall tasks is impaired by the presence of irrelevant background speech. According to the object-oriented episodic record (O-OER) model, this impairment is due to a conflict of order information from two different sources: the seriation of the irrelevant speech and the rehearsal of the order of the to-be-remembered items. We tested the model's prediction that irrelevant speech should impair performance on other tasks that involve seriation. Experiments 1 and 2 verified that both an irrelevant speech effect and a changing state effect would obtain in a between-subjects design in which a standard serial recall measure was used, allowing employment of a between-subjects design in subsequent experiments. Experiment 3 showed that performance on a sequence-learning task was impaired by the presence of irrelevant speech, and Experiment 4 verified that performance is worse when the irrelevant speech changes more (the changing state effect). These findings support the prediction made by the O-OER model that one essential component to the irrelevant speech effect is serial order information.     

Irrelevant Information and Mediated Intertemporal Choice

Results from 4 experiments suggest that currencies such as loyalty‐program points are overvalued. Different allocations of the same quantity of points across the same number of purchases (e.g., 100 points for each first, 200 for each second, 300 for each third purchase vs. 200 for each first, second, and third purchase) yielded irrelevant trends and should have led participants to ignore loyalty points as a basis for choice. However, choices were influenced by points even when consumers were provided with other truly discriminating information (e.g., price) and the irrelevance of the loyalty points was readily discernable. This implies that irrelevant information can influence choice when other, easily justifiable bases for decisions are available and, therefore, that irrelevant information can function as more than a tie‐breaker. Other implications for research on irrelevant attributes, medium effects, intertemporal choice, and loyalty programs are discussed.