Alhazen's Neglected Discoveries of Visual Phenomena

Perception ◽  
1996 ◽  
Vol 25 (10) ◽  
pp. 1203-1217 ◽  
Author(s):  
Ian P Howard
Keyword(s):  
Seventeenth Century ◽  
Visual Perception ◽  
Visual Motion ◽  
Eleventh Century ◽  
Binocular Disparity ◽  
Image Formation ◽  
Visual Pathways ◽  
Eye Muscles ◽  
Visual Phenomena ◽  
Direction Constancy

The first three books of the Book of Optics written by Alhazen in Cairo in the eleventh century were translated into English by A I Sabra in 1989. Book I deals with optics, the structure of the eye, image formation in the eye, and with the visual pathways. This book inspired all other books on optics from the thirteenth to the seventeenth century and formed the basis upon which Kepler solved the problem of image formation. However, Alhazen's work contained in Books II and III has been almost totally ignored. These two books contain an account of hundreds of observations and experiments carried out by Alhazen on a broad range of topics which are now studied under the heading of visual perception. He clearly enunciated many of the fundamental principles which are credited to scientists living in the last two hundred years, including a theory of unconscious inference; the law of equal innervation of the eye muscles; the principles of binocular direction; constancy of size, shape, and colour; induced visual motion; the vertical horopter; the fusional range of binocular disparity; and many others.

Who Is the Founder of Psychophysics and Experimental Psychology?

1999 ◽  
Vol 16 (2) ◽  
pp. 1-26
Author(s):  
Omar Khaleefa
Keyword(s):  
Visual Perception ◽  
Experimental Method ◽  
Experimental Psychology ◽  
Visual Illusion ◽  
Eleventh Century ◽  
Central Place ◽  
Psychological Explanation ◽  
Moon Illusion ◽  
New Concepts ◽  
History Of

The study is an investigation of the origins of psychophysics and experimentalpsychology. According to historians of psychology. FrancisBacon had the most crucial influence in the history of the experimentalmethod, because he emphasized the importance of induction, skepticism,quantification, and observation. The present study, however,attempts to show that Ibn al-Haytham laid the foundations of the aboveaspects of the experimental method. Furthermore, a number of historiansof psychology believe that Fechner was the founder of psychophysicswith his application “Filements of Psychophysics” in 1860.This study shows that in the eleventh century, Ibn al-Haytham made anoriginal contribution to the study of vision, wherein his psychophysicsborrowed its structure from physics and its spirit from psychology.Several aspects of visual perception were investigated by him, includingsensation (which occupies a central place in psychophysics), variationsin sensitivity, perception of colors. sensation of touch, perceptionof darkness, the psychological explanation of moon illusion, and binocularvision. This study presents five experiments by Ibn al-Haythamregarding the errors of vision, which is called in contemporary psychology“visual illusion.” These experiments have been applied andverified in Bahrain from both the physical and psychological perspectives.Finally, the study concludes that Ibn al-Haytham deserves the title“founder” of psychophysics as wellp the “founder” of experimentalpsychology. In this respect. Kitab ul-Manazir by Ibn al-Haytham.which appeared in the fmt half of the eleventh century, and not the“Elements of Psychophysics” by Fechner. which was published in thenineteenth century, marks the official “founding” of psychology,because it provides not only new concepts and theories but new methodsof measurement in psychology.

The Stigmata in Medieval and Early Modern Europe

2020 ◽  
Author(s):  
Carolyn Muessig
Keyword(s):  
Seventeenth Century ◽  
Middle Ages ◽  
Late Antiquity ◽  
Western Europe ◽  
Eleventh Century ◽  
Seventh Century ◽  
Introductory Overview ◽  
Devotional Practices ◽  
The Face ◽  
Biblical Commentaries

Francis of Assisi’s reported reception of the stigmata on Mount La Verna in 1224 is often considered to be the first account of an individual receiving the five wounds of Christ. The thirteenth-century appearance of this miracle, however, is not as unexpected as it first seems. Interpretations of Galatians 6:17—I bear the stigmata of the Lord Jesus Christ in my body—had been circulating in biblical commentaries since late antiquity. These works explained stigmata as wounds that martyrs received, like the apostle Paul, in their attempt to spread Christianity in the face of resistance. By the seventh century, stigmata were described as marks of Christ that priests received invisibly at their ordination. In the eleventh century, monks and nuns were perceived as bearing the stigmata in so far as they lived a life of renunciation out of love for Christ. By the later Middle Ages holy women like Catherine of Siena (d. 1380) were more frequently described as having stigmata than their male counterparts. With the religious upheavals of the sixteenth century, the way stigmata were defined reflected the diverse perceptions of Christianity held by Catholics and Protestants. This study traces the birth and evolution of religious stigmata as expressed in theological discussions and devotional practices in Western Europe from the early Middle Ages to the early seventeenth century. It also contains an introductory overview of the historiography of religious stigmata beginning in the second half of the seventeenth century to its treatment and assessment in the twenty-first century.

Christian Devotional Poetry and Sanskrit Hermeneutics

2018 ◽  
Vol 1 (1) ◽  
pp. 64-90
Author(s):  
Namrata Chaturvedi
Keyword(s):  
Seventeenth Century ◽  
Eleventh Century ◽  
Eighth Century ◽  
Interfaith Dialogue ◽  
Devotional Literature ◽  
Poetic Language ◽  
Devotional Poetry ◽  
Indian Christianity

This paper focuses on exploring dhvani as a hermeneutical tool for reading Christian devotional literature. Dhvani is a theory of poetic suggestion proposed by Ānandavardhana in the eighth century and elaborated upon by Abhinavagupta in the eleventh century that posits layers of semantics in poetic language. By focusing on the devotional poetry of the seventeenth-century religious poets of England, this paper argues for Ānandavardhana’s proposed poetics of suggestion as an enabling way of reading and cognizing devotion as a psycho emotive process. In the context of Indian Christianity, dhvani has been suggested by certain scholars as also enriching the possibilities of interfaith dialogue. This paper argues for incorporating poetic frameworks like dhvani as modes of interfaith dialogue, especially when reading Christian texts in India.

scholarly journals The Principles of Visual Perception Within The Context of Visual Illusions

2020 ◽  
Vol 8 (18) ◽  
Keyword(s):  
Visual Perception ◽  
Semantic Knowledge ◽  
Visual Illusions ◽  
Complex Information ◽  
Phenomenological Experience ◽  
Background Segmentation ◽  
Visual Phenomena ◽  
And Function ◽  
Effective Use ◽  
The Brain

In the transformation of the low-level, ambiguous retinal signal into a vivid and meaningful phenomenological experience, certain aspects are as essential as the input coming from the external environment. The semantic knowledge stored in memory, figure-background segmentation, grouping principles, and current mood and expectations of the person are equally important. Visual illusions, which might be described as the discrepancy between the objective properties of the external world and their subjective representations, is a common feature of the visual perception that provides meaningful insights with regards to the structure and function of the complex information processor in the brain. In this context, visual illusions are the end results of the optimization strategies that allow the effective use of limited neuronal and metabolic resources, and thus reflect the natural working principles while coping with these limitations, rather than restrictions inflicted upon the system. In this review, we present a compilation of illusions and summarize the key principles of visual perception on the basis of these visual phenomena. In the final section, we also discuss a number of recent topics within the context of Bayesian inference and psychopathology, illusions and alpha brain oscillations and time perception to describe the current directions in the field. Keywords Visual perception, visual illusions, visual system

Eye Signs, Syndromes, and Reviews and Opinions

2020 ◽  
pp. 232-240
Author(s):  
Louis R. Caplan
Keyword(s):  
Eye Movements ◽  
Visual Perception ◽  
Human Brain ◽  
Brain Activity ◽  
Guillain Barre Syndrome ◽  
Visual Environment ◽  
Loss Of Vision ◽  
Visual Phenomena ◽  
Guillain Barré ◽  
Abnormal Visual

Abstract: This chapter discusses Fisher’s contributions in regard to abnormalities of visual perception, eye appearance, and eye movements (“eye signs”) and also new syndromes, especially the Miller Fisher variant of Guillain–Barré syndrome. Much of human brain activity relates to visual perception and exploration of the visual environment—looking and seeing. Many of Fisher’s observations during his lifetime were related to the appearance of eye structures, loss of vision, abnormal visual phenomena, and movements of the eyes, qualifying him as one of the first neuro-ophthalmologists. Fisher also described a number of new syndromes and condition. In addition, he urged neurologists to engage in self-observation.

Noise Effects in Perceptual Models

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 44-44
Author(s):  
T D Wickens ◽  
L A Olzak
Keyword(s):  
Visual Perception ◽  
Spatial Frequency ◽  
Signal Detection ◽  
Intrinsic Variability ◽  
Noise Sources ◽  
Third Order ◽  
Noise Effects ◽  
Combination Process ◽  
Delta Sigma ◽  
Visual Phenomena

In studies of visual perception performance is often measured by statistics that are ratios of a perceptual magnitude to its intrinsic variability, most commonly the signal-detection measure d'=delta sigma. Many models for visual phenomena treat the variability sigma as a constant and describe performance exclusively by delta. However, in models for the combination of stimulus attributes, the combination process affects both terms, and an observed d' reflects both delta and sigma. For example, we have shown that masking and configural effects with sinusoidal plaids can be at least partially interpreted as noise effects. We have developed methods to analyse these effects. Through a series of concurrent-response experiments using grating stimuli, some reported at earlier ECVP meetings, we have measured the form and magnitude of the noise sources. Our analysis allows us to model the way that primitive Fourier components (spatial frequency by orientation) are integrated to form second-order or third-order combinations (eg spatial frequency pooled over orientation).

Al-Bīrūnī on Hermetic Forgery

2018 ◽  
Vol 3 (1) ◽  
pp. 54-66
Author(s):  
Kevin van Bladel
Keyword(s):  
Seventeenth Century ◽  
Central Asia ◽  
History Of Science ◽  
Eleventh Century ◽  
Reception History ◽  
History Of ◽  
Hermes Trismegistus

AbstractIn Central Asia in the early eleventh century, the Chorasmian scholar Abū Rayḥān al-Bīrūnī recognized that the Arabic works attributed to Hermes Trismegistus were inventions of recent centuries falsely written in the name of the ancient sage of legend. He did, however, accept the existence of a historical Hermes and even attempted to establish his chronology. This article presents al-Bīrūnī’s statements about this and contextualizes his view of the Arabic Hermetica as he derived it from Arabic chronographic sources. Al-Bīrūnī’s argument is compared with the celebrated seventeenth-century European criticism of the Greek Hermetica by Isaac Casaubon. It documents a hitherto unknown but significant event in the reception history of the Hermetica and helps to illustrate al-Bīrūnī’s attitude toward the history of science.

Eternalizing a Nation: ArmenianHishatakarans in the Seventeenth Century

2010 ◽  
Vol 79 (4) ◽  
pp. 783-799 ◽  
Author(s):  
Aida Gureghian
Keyword(s):  
Seventeenth Century ◽  
Sixteenth Century ◽  
Ethnic Groups ◽  
Eleventh Century ◽  
Well Being ◽  
The Caucasus ◽  
The People ◽  
Native Sovereignty

In 1514, the first battle between the Ottomans and the newly founded Safavid dynasty took place. The Battle of Chaldiran, as it came to be known, marked the beginning of a century-long struggle between the Sunni Ottomans and Shia Safavids that would draw to a close in 1639 with the Treaty of Zuhab. The human toll of this ongoing warfare over the Caucasus and Mesopotamia would be exacted not just from the soldiers of each empire, but also from the different ethnic groups that inhabited these regions. Some caught in the midst of these conflicts had their towns and homes razed by these troops. Others were forced to relocate and resettle. The Armenians were one such group, trapped between these Muslim forces, whose material and non-material well-being was under threat. Armenians had been coping with foreign incursions for centuries. Historical Armenia had been invaded and often laid to waste by the Arabs in the seventh, eighth, and ninth centuries, the Byzantines in the eleventh, and the Mongols and Seljuks from the eleventh to the fourteenth centuries. In fact, an Armenian kingdom in ancestral Armenia had not existed since the eleventh century, leaving the people of Greater (or historical) Armenia without any native sovereignty and as a politically fragmented entity. In the sixteenth century, historical Armenia had once again come to lie at the center of unremitting wars, this time fought between the Safavids and the Ottomans.

scholarly journals From credit to debt: A political history of English sovereign finance and money from the seventh century to the seventeenth

2019 ◽  
Vol 5 (1) ◽  
pp. 42-60
Author(s):  
Nicolas Dorn
Keyword(s):  
Seventeenth Century ◽  
Sovereign Debt ◽  
Eleventh Century ◽  
Seventh Century ◽  
Anglo Saxon ◽  
Modern Times ◽  
Sovereign Credit ◽  
History Of ◽  
Early Modern Times ◽  
New Perspective

This article provides a new perspective on sovereign finance and money in England from pre- modern to early modern times. Re-reading the literature on sovereign fiscality through the lens of sovereign jurisdictions and religious authority, it describes two distinct forms of sovereign finance: the rise and fall of sovereign credit from the seventh to eleventh century, followed by sovereign debt developing from the eleventh century into ‘modern’ sovereign debt from the seventeenth century onwards. In the early Anglo Saxon period, sovereign credit was given and received in non-monetised forms. It was when sovereign jurisdictions became too wide for labour and bulky produce to travel that tax was monetised. However, the monetisation of credit undermined the very sovereign-subject relation on which sovereign credit was based. After the introduction of short-term sovereign debt by the Normans, for the next five hundred years, the two distinct fiscal mechanisms of sovereign credit and sovereign debt ran in parallel, although the latter was restrained by the church’s prohibition of usury. In the seventeenth century, sovereign credit and sovereign debt became conjoined elements within one fiscal system, rather than separate mechanisms.

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