Misconvergence to the stimulus plane causes apparent displacement of the stimulus elements seen monocularly1

Abstract: When one binocularly views a group of vertical lines through a ring, the outermost line segments (one on each side) seen within the ring are seen monocularly while the segments of the same lines outside the ring are seen binocularly. The monocular segments appear to be displaced outward with respect to the center of the ring and with respect to the corresponding binocular segments outside the ring. Three experiments examined the extent and direction of this illusory displacement as a function of viewing distance, fixation disparity created by varying the angles of the two arms of a haploscope, and fixation disparity created by a stereoscope and different Nonius stimuli. The results of the experiments confirmed the hypothesis that the apparent displacement is due to misconvergence in accordance with Wells‐Hering's laws of visual direction.     

Existence questions

I argue that thinking of existence questions as deep questions to be resolved by a distinctively philosophical discipline of ontology is misguided. I begin by examining how to understand the truth-conditions of existence claims, by way of understanding the rules of use for ‘exists’ and for general noun terms. This yields a straightforward method for resolving existence questions by a combination of conceptual analysis and empirical enquiry. It also provides a blueprint for arguing against most common proposals for uniform substantive ‘criteria of existence’, whether they involve mind-independence, possession of causal powers, observability, etc., and thus for showing that many arguments for denying entities (numbers, ordinary objects, fictional characters, propositions…) on grounds of their failure to meet one or more of these proposed existence criteria are mistaken.

Abnormality, cognitive virtues, and knowledge

Causal analyses of one’s knowing that p have recently emphasized the involvement of cognitive virtues in coming to believe that p. John Greco suggests that in order to deal with Gettier-type cases, a virtue analysis of knowing should include a requirement that one’s knowing does not in a certain way involve abnormality. Yet Greco’s emphasis on statistical abnormality either renders his analysis subject to a generality problem or to objections regarding certain Gettier-type cases. When we instead consider abnormality in the sense of a causally differentiating factor in relation to a causal contrast situation, the account remains unclear concerning its application to an interesting non-Gettier-type case concerning chance. The exploration of these shortcomings casts doubt on the epistemological usefulness of the schema, ‘If you know, then there is no abnormality in your being right.’     

The Causal Chain Problem

This paper addresses a problem that arises when it comes to inferring deterministic causal chains from pertinent empirical data. It will be shown that to every deterministic chain there exists an empirically equivalent common cause structure. Thus, our overall conviction that deterministic chains are one of the most ubiquitous (macroscopic) causal structures is underdetermined by empirical data. It will be argued that even though the chain and its associated common cause model are empirically equivalent there exists an important asymmetry between the two models with respect to model expansions. This asymmetry might constitute a basis on which to disambiguate corresponding causal inferences on non-empirical grounds.

Bewitchment, biology, or both: the co-existence of natural and supernatural explanatory frameworks across development

Three studies examined the co-existence of natural and supernatural explanations for illness and disease transmission, from a developmental perspective. The participants (5-, 7-, 11-, and 15-year-olds and adults; N = 366) were drawn from 2 Sesotho-speaking South African communities, where Western biomedical and traditional healing frameworks were both available. Results indicated that, although biological explanations for illness were endorsed at high levels, witchcraft was also often endorsed. More important, bewitchment explanations were neither the result of ignorance nor replaced by biological explanations. Instead, both natural and supernatural explanations were used to explain the same phenomena, and bewitchment explanations were highest among adults. Taken together, these data provide insight into how diverse, culturally constructed belief systems about illness co-exist across development.     

Insight without cortex: lessons from the avian brain

Insight is a cognitive feature that is usually regarded as being generated by the neocortex and being present only in humans and possibly some closely related primates. In this essay we show that especially corvids display behavioral skills within the domains of object permanence, episodic memory, theory of mind, and tool use/causal reasoning that are insightful. These similarities between humans and corvids at the behavioral level are probably the result of a convergent evolution. Similarly, the telencephalic structures involved in higher cognitive functions in both species show a high degree of similarity, although the forebrain of birds has no cortex-like lamination. The neural substrate for insight-related cognitive functions in mammals and birds is thus not necessarily based on a laminated cortical structure but can be generated by differently organized forebrains. Hence, neither is insight restricted to mammals, as predicted from a “scala naturae”, nor is the laminated cortex a prerequisite for the highest cognitive functions.     

Tubes,tables and traps: great apes solve two functionally equivalent trap tasks but show no evidence of transfer across tasks

Previous studies on tool using have shown that presenting subjects with certain modifications in the experimental setup can substantially improve their performance. However, procedural modifications (e.g. trap table task) may not only remove task constraints but also simplify the problem conceptually. The goal of this study was to design a variation of the trap-table that was functionally equivalent to the trap-tube task. In this new task, the subjects had to decide where to insert the tool and in which direction the reward should be pushed. We also administered a trap-tube task that allowed animals to push or rake the reward with the tool to compare the subjects' performance on both tasks. We used a larger sample of subjects than in previous studies and from all the four species of great apes (Gorilla gorilla, Pan troglodytes, Pan paniscus, and Pongo pygmaeus). The results showed that apes performed better in the trap-platform task than in the trap-tube task. Subjects solved the tube task faster than in previous studies and they also preferred to rake in rather than to push the reward out. There was no correlation in the level of performance between both tasks, and no indication of interspecies differences. These data are consistent with the idea that apes may possess some specific causal knowledge of traps but may lack the ability to establish analogical relations between functional equivalent tasks.     

Causal perception of action-and-reaction sequences in 8- to 10-month-olds

Four experiments with 202 8- to 10-month-old infants studied their sensitivity to causation-at-a-distance in schematic events seen as goal-directed action and reaction by adults and whether this depends on attributes associated with animate agents. In Experiment 1, a red square moved toward a blue square without making contact; in “reaction” events blue moved away while red was approaching, whereas in “delay” events blue started after red stopped. Infants were habituated to one event and then tested on its reversal. Spatiotemporal features reversed for both events, but causal roles changed only in reversed reactions. Infants dishabituated more to reversed reaction events than to reversed delay events. Squares moved rigidly or in a nonrigid animal-like fashion. Infants discriminated these, but motion pattern did not affect responses to reversal. Infants also discriminated reactions from launching and dishabituated to reversed reactions lacking self-initiated motion. These results suggest that sensitivity to causation-at-a-distance depends on the event structure but not pattern or onset typical of animal motion.     

Flickers of Freedom and Modes of Action: A Reply to Timpe

In recent years, many incompatibilists have come to reject the traditional association of moral responsibility with alternative possibilities. Kevin Timpe argues that one such incompatibilist, Eleonore Stump, ultimately fails in her bid to sever this link. While she may have succeeded in dissociating responsibility from the freedom to perform a different action, he argues, she ends up reinforcing a related link, between responsibility and the freedom to act under a different mode. In this paper, I argue that Timpe’s response to Stump exploits concessions she need not have made. The upshot is that, contrary to what Timpe maintains, there is no reason to doubt that Stump's brand of incompatibilism is a genuine alternative to the traditional variety.