Jerry Fodor has consistently cited the persistence of illusions--especially the M.

The paper examines the philosophical implications of a phenomenon in the psychology of perception: the Mueller-Lyer illusion. In this visual effect, the impression is created that a horizontal line enclosed by acute angles is shorter than a similar line flanked by obtuse angles, though the lines are of equal length when measured with a ruler. While the Mueller-Lyer effect may be merely illusory when one adheres to the metrical laws of perceptual geometry based on Euclid, it is (...) suggested that, from a phenomenological standpoint, the effect has a validity of its own. Going further, the Mueller-Lyer configuration is adapted to provide an example of a form of visual experience that specifically violates one of Euclid's basic postulates. The article closes by exploring the possibility of non-Euclidean visual geometries in relation to the concept of causality, Einsteinian relativity, and anomalous phenomena. (shrink)

The Müller-Lyer illusion is the natural consequence of the construction of the vertebrate eye, retina and visual processing system. Due to imperfections in the vertebrate eye and retina and due to the subsequent processing in the system by ever increasing receptive fields, the visual information becomes less and less precise with respect to exact location and size. The consequence of this is that eventually the brain has to calculate a weighted mean value of the information, which is (...) spread out over a population of neurons. In the case of the Müller-Lyer illusion this inevitably leads to extension of one and reduction of the other line. The arguments presented explain several published experimental results concerning the Müller-Lyer illusion and shed new light upon the philosophical neutrality of observation sentences. (shrink)

The thematic survey of traditional literature uncovered a pressing need to study the M-L figure as a phenomenon in its own right. A design was constructed intending to evoke the figure's full phenomenal appearance. Instead of framing a highly determinate structure wherein a specific question is posed, E presented the figure to naive Ss, simply asking them to describe it. The purpose was to ascertain what naive Ss would perceive if not encumbered by a prior set. In addition, five experiential (...) questions about the descriptive task were included, aiming to elucidate and render intelligible the factual perceptions. The results showed that the M-L figure appears physiognomically. Typical responses exhibiting stylistic variation pointed to the dialectic between perceiver and perceived thing. A second finding was that the perception of equal horizontal lines as unequal emerged as a predominant, but only one of several possible ways of resolving the M-L figure's many perceptual possibilities. In fact, the data revealed a trend that elucidates the conditions which make possible the "M-L effect." Finally, "direction-orientation," a phenomenal variable elucidated by Merleau-Ponty's notions about the body and perception, emerged as the most characteristic way of perceiving the experimental figure. (shrink)

A fundamental question in the psychological sciences is the degree to which culture shapes core cognitive processes — perhaps none more foundational than how we perceive the world around us. A dramatic and oft-cited “case study” of culture’s power in this regard is the Müller-Lyer illusion, which depicts two lines of equal length but with arrowheads pointing either inward or outward, creating the illusion that one line is longer than the other. According to a line of (...) research stretching back over a century, depending on the society you were raised in (and how much carpentry you were exposed to), you may not see the illusion at all — an ambitious and influential research program motivating claims that seemingly basic aspects of visual processing may actually be “culturally evolved byproducts”. This Cultural Byproduct Hypothesis bears on foundational issues in the science, philosophy, and sociology of psychology, and remains popular today. Yet, here we argue that it is almost certainly false. We synthesize evidence from diverse fields which demonstrate that: (1) the illusion is not limited to humans, appearing in non-human animals from diverse ecologies; (2) the statistics of natural scenes are sufficient to capture the illusion; (3) the illusion does not require straight lines typical of carpentry (nor even any lines at all); (4) the illusion arises in sense modalities other than vision; and (5) the illusion arises even in congenitally blind subjects. Moreover, by reexamining historical data and ethnographic descriptions from the original case studies, we show that the evidence for cultural variation and its correlation with key cultural variables is in fact highly inconsistent, beset by questionable research practices, and misreported by later discussions. Together, these considerations undermine the most popular and dramatic example of cultural influence on perception. We further extend our case beyond this phenomenon, showing that many of these considerations apply to other visual illusions as well, including similarly implicated visual phenomena such as the Ebbinghaus, Ponzo, Poggendorf, and Horizontal-Vertical illusions. We conclude by outlining future approaches to cross-cultural research on perception, and we also point to other potential sources of cultural variation in visual processing. (shrink)

Examples of sensory illusion show the failure of the attempt of traditional sense-datum theory to account for something's phenomenally appearing to be F by postulating the existence of a sense-datum that is actually F. the Muller-Lyer Illusion cannot be explained by postulating two sensibly presented lines that actually have the lengths the physical lines appear to have. Illusions due to color contrast cannot be explained by postulating sense-data that actually have the colors the physical samples appear to (...) have. (shrink)

A number of perceptual (exteroceptive and proprioceptive) illusions present problems for predictive processing accounts. In this chapter we’ll review explanations of the Müller-Lyer Illusion (MLI), the Rubber Hand Illusion (RHI) and the Alien Hand Illusion (AHI) based on the idea of Prediction Error Minimization (PEM), and show why they fail. In spite of the relatively open communicative processes which, on many accounts, are posited between hierarchical levels of the cognitive system in order to facilitate the (...) minimization of prediction errors, perceptual illusions seemingly allow prediction errors to rule. Even if, at the top, we have reliable and secure knowledge that the lines in the MLI are equal, or that the rubber hand in the RHI is not our hand, the system seems unable to correct for sensory errors that form the illusion. We argue that the standard PEM explanation based on a short-circuiting principle doesn’t work. This is the idea that where there are general statistical regularities in the environment there is a kind of short circuiting such that relevant priors are relegated to lower-level processing so that information from higher levels is not exchanged (Ogilvie and Carruthers, Review of Philosophy and Psychology 7:721–742, 2016), or is not as precise as it should be (Hohwy, The Predictive Mind, Oxford University Press, Oxford, 2013). Such solutions (without convincing explanation) violate the idea of open communication and/or they over-discount the reliable and secure knowledge that is in the system. We propose an alternative, 4E (embodied, embedded, extended, enactive) solution. We argue that PEM fails to take into account the ‘structural resistance’ introduced by material and cultural factors in the broader cognitive system. (shrink)

In the reported, experiment participants hit a ball to aim at the vertex of a Müller–Lyer configuration. This configuration either remained stable, changed its shaft length or the orientation of the tails during movement execution. A significant illusion bias was observed in all perturbation conditions, but not in the stationary condition. The illusion bias emerged for perturbations shortly after movement onset and for perturbations during execution, the latter of which allowed only a minimum of time for (...) making adjustments . These findings indicate that allocentric information is exploited for online control when people make rapid adjustments in response to a sudden change in the environment and not when people guide their limb movements to interact with a stable environment. (shrink)

Experiments are presented showing that visual search for Mueller-Lyer (ML) stimuli is based on complete configurations, rather than component segments. Segments easily detected in isolation were difficult to detect when embedded in a configuration, indicating preemption by low-level groups. This preemption—which caused stimulus components to become inaccessible to rapid search—was an all-or-nothing effect, and so could serve as a powerful test of grouping. It is shown that these effects are unlikely to be due to blurring by simple spatial filters (...) at early visual levels. It is proposed instead that they are due to more sophisticated processes that rapidly bind contour fragments into spatially-extended assemblies. These results support the view that rapid visual search cannot access the primitives formed at the earliest stages of visual processing; rather, it can access only higher-level, more ecologically-relevant structures. (shrink)

In this study, we explored the time and space relationship according to two different spatial codings, namely, the left/right extension and the reachability of stimulus along a near/far dimension. Four experiments were carried out in which healthy participants performed the time and spatial bisection tasks in near/far space, before and after short or long tool-use training. Stimuli were prebisected horizontal lines of different temporal durations in which the midpoint was manipulated according to the Muller-Lyer illusion. The perceptual illusory (...) effects emerged in spatial but not temporal judgments. We revealed that temporal and spatial representations dynamically change according to the action potentialities of an individual: temporal duration was perceived as shorter and the perceived line’s midpoint was shifted to the left in far than in near space. Crucially, this dissociation disappeared following a long but not short tool-use training. Finally, we observed age-related differences in spatial attention which may be crucial in building the memory temporal standard to categorize durations. (shrink)

Various illusions of meaning appear to be insensitive to counter-evidence. That is, in a similar fashion to the well-known Müller-Lyer illusion in vision, certain illusions of meaning seem not to fade away even after one endorses beliefs that rebut the illusion one is having. Such apparently evidence-insensitive illusions have been employed to support the view that we can perceive meanings because evidence-insensitivity is typically taken to be a perceptual trait. In this paper, I offer a comprehensive (...) examination of allegedly evidence-insensitive illusions of meaning and argue that none is, in fact, evidence insensitive in a way that might support the view that we can perceive meanings. (shrink)

Most inferentialists hope to bypass givenness by tracking the conditionals claimants are implicitly committed to. I argue that this approach is underdetermined because one can always construct parallel trees of conditionals. I illustrate this using the Müller-Lyer illusion and touching a table. In the former case, the lines are either even or uneven; in the latter case, a moving hand will either sweep through or be halted. For each possibility, we can rationally foresee consequents. However, I argue (...) that, until and unless we benefit from what is given in experience, we cannot know whether to affirm the antecedents of those conditionals. (shrink)

Despite the various perceptual-motor deficits documented in strabismus, there is a paucity of studies evaluating visual illusions in patients with strabismus. The aim of this study was to examine how the illusionary perception occurs in children/adolescents with strabismus with referral for surgery to correct ocular deviations. A controlled cross-sectional study was carried out in which 45 participants with strabismus and 62 healthy volunteers aged 10–15 years were evaluated. The behavioral response to three geometric illusions [Vertical-Horizontal illusion, Müller-Lyer (...) illusion and Ponzo illusion] and respective neutral stimuli regarding the estimation of image size and response time were measured using the Method of Adjustment. To analyze the influence of secondary factors: type of ocular deviation ; amount of eye deviation; presence of amblyopia and stereopsis, a one-way ANOVA was performed. Among the tested illusions, children with strabismus showed greater susceptibility and response time to Ponzo’s illusory images. Children with strabismus and preserved stereopsis, on the other hand, showed similar susceptibility and response time to control group patients to the Ponzo illusion. Patients with amblyopia showed overcorrection in the estimate of non-illusory Ponzo images. Children with horizontal ocular deviation associated with vertical deviation showed higher susceptibility to vertical adjustment images for the Müller-Lyer illusion. Individuals with strabismus tended to overcorrect the length of the straight-line segment adjusted for non-illusory images when testing non-illusory images in the Müller-Lyer test, as well as for the neutral images in the Vertical-Horizontal test. The findings indicated impairment in the perception of geometric illusions and neutral figures, especially for the Ponzo illusion test by children with strabismus. As the behavioral response to illusory images may indirectly reflect the visual and morphofunctional alterations present in these individuals, we suggest that the investigation of visual illusory perception can be used as a new research strategy in the field of investigating the visual function in strabismus. (shrink)

The paper confronts the disagreement argument for relativism about matters of taste, defending a specific form of contextualism. It is first considered whether the disagreement data might manifest an inviariantist attitude speakers pre-reflectively have. Semantic and ontological enlightenment should then make the impressions of disagreement vanish, or at least leave them as lingering ineffectual Müller-Lyer-like illusions; but it is granted to relativists that this does not fully happen. López de Sa’s appeal to presuppositions of commonality and Sundell’s appeal (...) to metalinguistic disagreement are discussed, and it is argued that, although they help to clarify the issues, they do not fully explain why such impressions remain under enlightenment. To do it, the paper develops a suggestion that other writers have made, that the lingering impression of disagreement is a consequence of a practical conflict, appealing to dispositions to practical coordination that come together with presuppositions of commonality in axiological matters. (shrink)

Why do design arguments—particularly those emphasizing machine metaphors such as “Organisms and/or their parts are machines”—continue to be so convincing to so many people after they have been repeatedly refuted? In this essay I review various interpretations and refutations of design arguments and make a distinction between rationally refuting such arguments (RefutingR) and rendering them psychologically unconvincing (RefutingP). Expanding on this distinction, I provide support from recent work on the cognitive power of metaphors and developmental psychological work indicating a basic (...) human propensity toward attributing agency to natural events, to show that design arguments “make sense”unless one is cued to look more closely. As with visual illusions, such as the Müller-Lyer arrow illusion, there is nothing wrong with a believer's cognitive apparatus any more than with their visual apparatus when they judge the lines in the illusion to be of unequal length. It takes training or a dissonance between design beliefs and other beliefs or experiences to play the role that a ruler does in the visual case. Unless people are cued to “look again” at what initially makes perfect sense, they are not inclined to apply more sophisticated evaluative procedures. (shrink)

The dominant view of the ventral and dorsal visual systems is that they subserve perception and action. De Wit, Van der Kamp, and Masters suggested that a more fundamental distinction might exist between the nature of information exploited by the systems. The present study distinguished between these accounts by asking participants to perform delayed matching , pointing and perceptual judgment responses to masked Müller–Lyer stimuli of varying length. Matching and pointing responses of participants who could not perceptually judge (...) stimulus length at brief durations remained sensitive to veridical stimulus length , but not the illusion , which was effective at long durations. Distinct thresholds for egocentric and allocentric information pick up were thus evident irrespective of whether perception or action responses were required. It was concluded that the dorsal and ventral systems may be delineated fundamentally by fast egocentric- and slower allocentric information pick up, respectively. (shrink)

Introduction to sensory psychology, by C. Mueller.--Some reflections on brain and mind, by R. Brain.--In search of the engram, by K. Lashly.--Cerebral organization and behavior, by R. W. Sperry.--Relations between the central nervous system and the peripheral organs, by E. von Holst.--Effects of the Gestalt revolution, by J. E. Hochberg.--Seeing in depth, by R. L. Gregory.--The stimulus variables for visual depth perception, by J. J. Gibson.--The elaboration of the universe, by J. Piaget.--Visual perception approached by the method of stabilized images, (...) by R. M. Pritchard, W. Heron, and D. O. Hebb.--Philosophy as rigorous science, by E. Husserl.--The "sensation" as a unit of experience, by M. Merleau-Ponty.--The phenomenology of perception: perceptual implications, by A. Gurwitsch.--The expression of thinking, by E. W. Straus.--The concept of group and the theory of perception, by E. Cassirer.--Norm and pathology of I-world relations, by E. W. Straus.--The metaphysical in man, by M. Merleau-Ponty.--Cultural differences in the perception of geometric illusions, by M. H. Segall, D. T. Campbell, and M. J. Herskovits.--The interpretive cortex, by W. Penfield.--Recovery from early blindness: a case study, by R. L. Gregory and J. G. Wallace.--Visual disturbances after perceptual isolation, by W. Heron, B. K. Doane, and T. H. Scott. (shrink)

This essay investigates the dichotomy between appearance and reality. We will look into some emblematic examples, like the Müller-Lyer optical illusion and the Gelb effect, in order to show how a careful phenomenological analysis overcomes all forms of dualism about the experience of the external world. The aforementioned phenomenological approach is based on immediate experience and, more broadly, contributes to the methodology of experimental phenomenology.

Topology has been characterized as an unsuitable mathematical framework for the investigation of geometric-perceptual phenomena. This has been attributed to the highly abstract nature of topology leading to failures in tasks such as making distinctions between geometrical figures (e.g., a cube versus a sphere) in which the human perceptual system succeeds easily. An alternative thesis is proposed on both philosophical and empirical grounds. The present analysis applies the Müller-Lyer (ML) illusion as a method of investigation to examine (...) the suitability of topology in raising questions about geometric-perceptual phenomena and formulating potential answers to these questions. Not only will it be concluded that topology is a suitable mathematical framework in which one can formulate relevant questions and potential answers with respect to perceptual phenomena such as the ML illusion, it will also be discussed that topology will not be replaced by other means of spatial representation consistent with the findings that indicate its contributions to our daily spatial behavior along with other means such as Euclidean geometry. In addition, the analysis will be discussed with respect to two relevant themes: 1) the implications of the proposed view in relation to Husserl’s phenomenology and 2) the effect of developmental stages and education that may change the involvement of topology in such perceptual responses over time. (shrink)

Though much progress has been made on inclusion of non-pregnant women in research, thoughtful discussion about including pregnant women has lagged behind. We outline resulting knowledge gaps and their costs and then highlight four reasons why ethically we are obliged to confront the challenges of including pregnant women in clinical research. These are: the need for effective treatment for women during pregnancy, fetal safety, harm from the reticence to prescribe potentially beneficial medication, and the broader issues of justice and access (...) to benefits of research participation. Going forward requires shifting the burden of justification from inclusion to exclusion and developing an adequate ethical framework that specifies suitable justifications for excluding pregnant women from research. (shrink)

Reasoning well about risk is most challenging when a woman is pregnant, for patient and doctor alike. During pregnancy, we tend to note the risks of medical interventions without adequately noting those of failing to intervene, yet when it's time to give birth, interventions are seldom questioned, even when they don't work. Meanwhile, outside the clinic, advice given to pregnant women on how to stay healthy in everyday life can seem capricious and overly cautious. This kind of reasoning reflects fear, (...) not evidence. (shrink)

This book represents a considerable revision and expansion of Public Choice II. Six new chapters have been added, and several chapters from the previous edition have been extensively revised. The discussion of empirical work in public choice has been greatly expanded. As in the previous editions, all of the major topics of public choice are covered. These include: why the state exists, voting rules, federalism, the theory of clubs, two-party and multiparty electoral systems, rent seeking, bureaucracy, interest groups, dictatorship, the (...) size of government, voter participation, and political business cycles. Normative issues in public choice are also examined including a normative analysis of the simple majority rule, Bergson–Samuelson social welfare functions, the Arrow and Sen impossibility theorems, Rawls's social contract theory and the constitutional political economy of Buchanan and Tullock. (shrink)

Pregnant women and their interests have been underrepresented in health research. Little is known about issues relevant to women considering research participation during pregnancy. We performed in-depth interviews with 22 women enrolled in either one of two trials sponsored by the National Institutes of Health to assess the safety and immunogenicity of the H1N1 vaccine during pregnancy. Three themes characterized women’s decisions to participate in research: they valued early access to the vaccine, they perceived a safety advantage when participating in (...) research, and they wanted to help advance scientific knowledge. However, there were also some considerations that would disincline them to participate in research—for instance, a significant risk of maternal or fetal harm, the presence of a placebo arm in a study, or a requirement to significantly change planned therapy or behavior. Pregnant women who participated in the H1N1 vaccine trials viewed research favorably, citing its advantages over standard clinical care. These findings emphasize that access to benefit should guide policy for including pregnant women in research. (shrink)