Do we perceive a flattened world on the monitor screen?

The current model of three-dimensional perception hypothesizes that the brain integrates the depth cues in a statistically optimal fashion through a weighted linear combination with weights proportional to the reliabilities obtained for each cue in isolation (Landy, Maloney, Johnston, & Young, 1995). Even though many investigations support such theoretical framework, some recent empirical findings are at odds with this view (e.g., Domini, Caudek, & Tassinari, 2006). Failures of linear cue integration have been attributed to cue-conflict and to unmodelled cues to flatness present in computer-generated displays. We describe two cue-combination experiments designed to test the integration of stereo and motion cues, in the presence of consistent or conflicting blur and accommodation information (i.e., when flatness cues are either absent, with physical stimuli, or present, with computer-generated displays). In both conditions, we replicated the results of Domini et al. (2006): The amount of perceived depth increased as more cues were available, also producing an over-estimation of depth in some conditions. These results can be explained by the Intrinsic Constraint model, but not by linear cue combination.     

Is knowledge a natural kind?

The project of treating knowledge as an empirical object of study has gained popularity in recent naturalistic epistemology. It is argued here that the assumption that such an object of study exists is in tension with other central elements of naturalistic philosophy. Two hypotheses are considered. In the first, “knowledge” is hypothesized to refer to mental states causally responsible for the behaviour of cognitive agents. Here, the relational character of truth creates a problem. In the second hypothesis “knowledge” is hypothesized to refer to mental states causally responsible for the evolutionarily successful behaviour of cognitive agents. Here, the problem lies in the fact that evolution by natural selection is not necessarily conducive to truth. The result does not necessarily amount to eliminativism, however, since the naturalist may consistently reject the condition of truth that lies behind these problems.     

Do 9-month-olds perceive causation-at-a-distance?

Humans understand mechanical events to involve physical bodies interacting by contact, but intentional events involve agents that can also interact at a distance. We investigated infant sensitivity to causality in a simple event in which one agent appears to react to another without contact. Infants 9 months old were habituated to one of two events involving a computer-animated red square moving nonrigidly--like a caterpillar--towards a green square. In the 'reaction event', the green object moved in turn before the red one stopped, while in the 'pause event' the green object moved after the red one stopped. After habituation, each infant saw the habituation movie played in reverse. This test involved identical spatiotemporal changes for reaction and pause event, but the reversed reaction additionally involved a change in the causal roles. Infants dishabituated to reversal of the reaction but not the pause event, a result which suggests sensitivity to causation-at-a-distance. This ability could support development of social cognition and theory of mind.     

Can we perceive mental states?

Synthese - In this paper, I defend Non-Inferentialism about mental states, the view that we can perceive some mental states in a direct, non-inferential way. First, I discuss how the question of...     

Can we correctly perceive the reaching range of others?

Little is known about our ability to predict the motor capacities of other people. This study explored how observers perceive the reaching range of another person by asking them to judge the reachability of a moving object. Experiments 1 and 2 found that observers overestimated the reaching ranges of both short and tall people. Estimates were larger when objects moved towards rather than away from the person. Experiment 3 showed that perceived reaching range depended on the observer's viewing perspective. Compared with previous findings, these results suggest that observers use different cognitive operations to mentally simulate actions for themselves vs. others. They also inform the current debate about motor imagery and action understanding.     

Do pigeons (Columba livia) perceive object unity?

Human infants perceive two rods moving in concert behind an occluder as one unitary rod. In four experiments we tested whether pigeons also perceive unity of objects. Pigeons were trained on a matching-to-sample task to discriminate between one unitary rod moving at a constant speed and two aligned rods moving together at the same speed. The latter stimulus was identical to the former except for a gap in the center. In experiment 1, we tested pigeons in probe trials in which a rectangle occluded the center of the sample rods, to see which comparison stimulus, the unitary rod or the aligned two rods, the subjects would match to the sample. Two of the three subjects pecked at the two rods significantly more often than at the unitary rod. In experiment 2, we trained the same pigeons to match the sample rods moving "in front of" the occluder. Pigeons persisted in matching two separate rods to the unitary rod moving in front of the occluder. In experiments 3 and 4, we used a parallelogram and an undulating shape as the occluder to alter the shape and the size of the portions above and below the occluder by the motion of the sample rods. Both subjects chose the two rods significantly more often than chance in experiment 3 and one of them did so in experiment 4. The results suggest that pigeons do not complete occluded portions even though the two elements move in concert. These negative results suggest that some alternative way of identifying objects may have evolved in pigeons. Accepted after revision: 2 May 2001 Electronic Publication     

Do we weep for Cordelia?

Abstract

Much of the contemporary debate concerning the nature and role of fictive emotions has argued that we do feel garden-variety emotions for fictional characters; the puzzle has been to account for this, given our knowledge of their fictional status. In this paper I argue that many of the emotional responses we have towards fictional characters are nothing like the emotions we feel in ordinary life. The implications for our engagement with literary fictions are subsequently examined.     

Do we need visual subjects?

It is widely accepted within contemporary philosophy of perception that the content of visual states cannot be characterized simply as a list of represented features. This is because such characterization leads to the so-called ‘Many Properties’ problem, that is, it does not allow us to explain how the visual system is able to distinguish between scenes containing different arrangements of the same features. The usual solution to the Many Properties problem is to characterize some basic elements of content as subjects, to which features are attributed by a predication-like relation. In this paper, I reconsider this solution and claim that the Many Properties problem can be solved without postulating such subjects. What is more, I argue that an alternative approach has stronger justification given the empirical data concerning human vision.     

Do we conceptualize every color we consciously discriminate?

Mandik understands color-consciousness conceptualism to be the view that one deploys in a conscious qualitative state concepts for every color consciously discriminated by that state. Some argue that the experimental evidence that we can consciously discriminate barely distinct hues that are presented together but cannot do so when those hues are presented in short succession suggests that we can consciously discriminate colors that we do not conceptualize. Mandik maintains, however, that this evidence is consistent with our deploying a variety of nondemonstrative concepts for those colors and so does not pose a threat to conceptualism. But even if Mandik has shown that we deploy such concepts in these experimental conditions, there are cases of conscious states that discriminate colors but do not involve concepts of those colors. Mandik's arguments sustain only a theory in the vicinity of conceptualism: The view that we possess concepts for every color we can discriminate consciously, but need not deploy those concepts in every conscious act of color discrimination.     

Do visual images have gestalt properties?

Recent research has demonstrated that percepts and images share processing resources. A natural consequence of this evidence is to ask what kind of properties are shared by the two representational systems, i.e. images and percepts. To what degree, for example, do images share the complex organization of visual percepts?

This paper investigates whether percepts and images share Gestalt properties. Four experiments were conducted to study this hypothesis. In all experiments subjects were presented with an auditory message in which approximately 15 locations in a matrix were defined by giving the co-ordinates of the cells. Half of the stimuli presented some “good” form, whereas in the other half the locations of the pieces were scattered. Subjects were systematically less able to recall the locations of the random forms. Therefore, it could be argued that the “good” forms help in image construction, even though the elements were auditorily presented. Effects of varying presentation speed, order, and of requiring a mental rotation before recall support this conclusion.     

‘Knowledge’ as a natural kind term

Naturalists who conceive of knowledge as a natural kind are led to treat ‘knowledge’ as a natural kind term. ‘Knowledge,’ then, must behave semantically in the ways that seem to support a direct reference theory for other natural kind terms. A direct reference theory for ‘knowledge,’ however, appears to leave open too many possibilities about the identity of knowledge. Intuitively, states of belief count as knowledge only if they meet epistemic criteria, not merely if they bear a causal/historical relation to the term. I will develop this objection and show that it is grounded in modal considerations central to Kripke’s work on reference. I will also argue that a more plausible externalist semantics for natural kind terms disarms the objection.     

What kind of kind is intelligence?

The model of human intelligence that is most widely adopted derives from psychometrics and behavioral genetics. This standard approach conceives intelligence as a general cognitive ability that is genetically highly heritable and describable using quantitative traits analysis. The paper analyzes intelligence within the debate on natural kinds and contends that the general intelligence conceptualization does not carve psychological nature at its joints. Moreover, I argue that this model assumes an essentialist perspective. As an alternative, I consider an HPC theory of intelligence and evaluate how it deals with essentialism and with intuitions coming from cognitive science. Finally, I highlight some concerns about the HPC model as well, and conclude by suggesting that it is unnecessary to treat intelligence as a kind in any sense.     

Do infants perceive the social robot Keepon as a communicative partner?

This study investigates if infants perceive an unfamiliar agent, such as the robot Keepon, as a social agent after observing an interaction between the robot and a human adult. 23 infants, aged 9–17 month, were exposed, in a first phase, to either a contingent interaction between the active robot and an active human adult, or to an interaction between an active human adult and the non-active robot, followed by a second phase, in which infants were offered the opportunity to initiate a turn-taking interaction with Keepon.The measured variables were: (1) the number of social initiations the infant directed toward the robot, and (2) the number of anticipatory orientations of attention to the agent that follows in the conversation. The results indicate a significant higher level of initiations in the interactive robot condition compared to the non-active robot condition, while the difference between the frequencies of anticipations of turn-taking behaviors was not significant.     

Do we all look alike to computers?

People are better able to recognize faces of their own race than those of other races. One explanation is that this 'other-race effect' is caused by lifelong experience in which faces from some races are more common than other races. A recent article by Furl et al. tests experience-based accounts of the other-race effect by giving computer algorithms of face recognition training on preponderantly Caucasian faces. The only algorithms that reliably produced other-race effects were those that created face representations distorted to emphasize features that individuated faces.     

Do we need a concept of disease?

The terms “health”, “disease” and “illness” are frequently used in clinical medicine. This has misled philosophers into believing that these concepts are important for clinical thinking and decision making. For instance, it is held that decisions about whether or not to treat someone or whether to relieve someone of moral responsibility depend on whether the person has a disease. In this paper it is argued that the crucial role of the ‘disease’ concept is illusory. The health/disease distinction is irrelevant for most decisions and represents a conceptual straightjacket. Sophisticated and mature clinical decision making requires that we free ourselves from the concept of disease.