Visual Perception Flashcards
(24 cards)
Thinking about seeing - overview
Use of the topic of visual perception for example of how psych switched from philosophy to experimental, scientific psychology
Many people had concerns about unreliability of the senses. For Plato, what we know, or can know, cannot be derived exclusively from the senses - there is an ‘ideal’ realm of abstract ideas and forms
Our understanding of how vision works has been built upon developments in maths, physics, astronomy
But experimental study of visual perception (as opposed to optics, emerged relatively recently)
Extramission theories: included Euclid (c. 300BC) and Plato (c.350 B-CELLS) says a stream of light 0r fire comes from the eyes to allow us to see objects
- however, we cannot see in the dark
Intromission theories: e.g. the atom (from Democritus c.400BCE) - objects cast off some kind of material substance that enters the eye
Epicurus (c.300BCE) - objects cast off one-atom thick layers that drive in the eye (this at least made sense of object constancy)
Aristotle (ca. 330BCE)
Rejected the extramssion theory - due to not being able to see in the dark
Aristotle and his pupil Theophrastus had a more modern concept - light was generated by the sun and reflected from objects. It travelled through a medium (air) to the eye. Without this medium, we would see nothing
His visual theory De Anima 11. 7, he said the visual organ and its visual ability are inextricable, thereby the visual ability is the form of the visual organ, and the visual organ is the mater of the visual ability (Qi Zhao, 17 October 2023)
He had a single, static conception of light and be believed that illumination occurs prior to and independent of the action of colours (SM Costello, 2020)
Alhazen
(965-1040 CE0
Born in Basra, Iraq/Persia, died in Cairo (probably)
Allegedly wrote his most important work of optics while under House arrest, including “The Book of Optics”
- important to development of optics as it laid the foundationsnof modern physical optics after drastically transforming the way in which light and vision had been understood (History of information)
“Father of modern optics” with studies of stereopsis, refraction, and several illusions including the moon illusion
Hugely reflected later European work
Rays origin are from objects, not eyes
- sight does not perceive any visible object unless there exists in the object some light which the object possesses itself or which radiates upon from other object
Vision occurs in the brain, not eyes
Expiernce affects perception and hence perception can b mistaken
His work on visual perception led him to the camera obscure and image inversion in the eye and heavily advocated for the use of mathematical concepts to in understanding visual phenomena (Philosophy of Cosmology)
Wrote more than 200 works over his life time
Also carried out the first experiments on the dispersion of light into colours
Looked into many visual phenomena like shadows, eclipses, the rainbow and the physical nature of light, as well as trying to explain binocular vision
The methods he used were also highly scientific, and he developed rigorous experimental methods of controlled scientific testing in order to verify theoretical hypotheses hence why he is often referred to as the first scientist (Abdelghani Tbakhi, Samir S Air, 2007)
17th century physics
Johannesburg Kepler (1571-1630)
“Thus vision is brought about by a picture of a thing seen being formed on the concave surface of the retina” (1964)
Kepler’s discovery of the path of light in the eye made is possible to explain the following physical phenomena
- central visual acuity
- visual field
- dark adaption
- errors of refractions
Also formatted the law stating that the intensity of light decreases with th square distance
W Jaeger (February 1989)
But not all aspects of his thinking seem quite so modern -> suggested that the image seen in the translated in a way by the souk
Sir Issac Newton (1643-1727) among many other contributors he used prisms to decompose white light into its spectral components
- placed a prism in front of sunlight in a position so that it would refract onto the opposite wall
- saw that when white light passed through prism, it changed direction and separated into a rainbow ( V Cain 2012)
18th century philosophy
Fundamental question: if starting point for seeing 2D retinal image, how do we see a 3D world?
Most explanations seen is as learned:
- Locke (1690) and Berkley (1709) - British empiricist philosophers for whom there was no innate ideas and said that we learnt
- however, their views were opposing
- Locke believed in the existence of an external world with “primary qualities” (like shape and size) that exist independently of perception, while Berkley argued that objects are mind-dependents and only exist as ideas or perceptions (Alessandro Colarossi 2019)
Contrasts with:
- Immanuel Kants (1724-1904): rejects the empiricist position that all knowledge is learned and suggested tax tether must be some inborn assumptions or categories
- theory of “transcendent idealism”
- our perception isn’t a passive reception of external stimuli, but an active construction involving sensory input and the mind’s innate structures (Cathrine Wilson May 2022)
Nature vs nurture theme in history of psych
19th century psychophysics
Aimed at discovering quantitate laws linking psychology and physics
- in particularly, they were many to connect physical entities of stimulus to the resulting psychological intensities of stimulus to the resulting psychological intensities of sensation (Louis Narens, Bryan Skyrms, September 2020)
Systematic study of the relationship between sensations and physical events e.g. how brightness (perceiver) is related to luminance (object)
Two influential scientists in Leipzig
Gustavia Fechner (1801-1887) introduced the term. He published the ‘Elements of Psychophysics’ in 1860, laying out the fields principles and methods
- his logarithmic scale, known as the Flecher scale, was a key contribution
- also established the “Weber-Fechner Law” which quantifies the relationship between physical stimuli and subjective sensation (Anne Kamiya, November 21 2023)
Ernst H Weber (….. - 1878) noticed that JDN is some sensory dimension or other is a constant proportion of usual about 3%
- conducted experiments on perception of weight temperature and pressure
- Webber fraction constant
He also conducted experiments on the sense of touch and light, particularly focusing on the “just noticeable difference” (JND) (Louis Narens, Brian Skyrms September 2020)
Fechner et al introduced methods still used today e.g. methods of limits, methods of constant stimuli
- invented the term psychophysics
Herman von Helmholtz
- Brief biography -
1821-1894
Studied medicine (Johannesburg Muller)
1856 published ‘Handbook of Physiological Optics Vol 1’
1856 - chair of Physiology at Heidelberg
1871 - chair of Physics at Berlin - some psychologically-relevant and enduring scientific contributions -
Invented ophthalmoscope
Association and empiricist doctrine
Unconscious interference
Theory of depth perception (bias visual cues plus felt positions in space learned by association)
Young-Helmholtz trichromatic theory of colour perception
According to his ‘projection’ theory of the physiology of perception, a stimulus causes is response directly
That is, our nerves are malleable, like wax, and the objects “projects” signals onto the nerve endings directly, like keys pressed into the wax (Lydia Pattom September 2024)
He had a very nature based approach, evident in all of hisnwork
He insisted that an organism as a whole was greater than the sum of its physiological parts
in 1859, he was able to calculate the speed of a nerve impulse that was measured by Müller. This was 90 feet/27 metres per second (measured by the invention of the myograph)
This supported their theory of vitalism
Invented the ophthalmoscope and the ophthalmomter, both in 1851, which allows light to be focused onto he retina
Still regularly used by physicians today to examine retinal blood vessels and detainee high blood pressure and arterial disease in the eye
Helmholtz (1867)
Second volume of his book “Handbook of Physiological Optics” (first volume released in 1856)
“The sensations of the sense are tokens of our consciousness, it being left to our intelligence to learn how to comprehend their meaning”
“Such subjects are always imagined as being present in the field of vision as would have there in order to produce the same impression on the nervous system”
“The psychic activities that lead us to infer that there in front of us at a certain place there is a certain object of a certain charter, are generally not conscious activites, but unconscious ones. In their result, they are equivalent to a conclusion”
Perception is indirect and inferential. In this view, visual illusions are fidence of these inferential processes
The birth place of experimental psychology
Wilhelm Maximilian Wundt (1832-1920)
Had previously studied with Muller and worked at Heidelberg with Helmholtz
University of Leipzig recognised his laboratory in 1879 - the ‘first’ psychological lab (contemporary with James in the US)
Certainly at/the ‘founding father’. The first generation of experimental psychologists were all influenced by, many studies with, Wundt
Clearly a distinguished an ‘experimental’ psychology (e.g. of th senses) from ‘social’ psychology
(Even within EP -> some of Wind’s methods appear ‘less scientific’ than you might suppose, by characterised by attempt to control the setting)
Psychology as the science of consciousness. Task is to show how elements on consciousness are combined to form perceptions and ideas. Introspection was used to do this
Developed experimental methods to study mental pro ease,s including sensation and perception, and explored th role of these processes in how er perceive the world. Focused on analysing visual illusions like the Wundt illusion, where straight lines appeared curved, and the Herring illusion, helping to understand how the Bain interprets visual information (Kendra Cherry, March 17 2025)
Also very influential in other areas of psychology. He was the person who separates psychology from philosophy by Analysing the workings of the mind in a structured way
His aim was to record thoughts and sensations, and to analyse them into their constituent elements in order to get at the underlying strcuture
Founded the school coffee psychology and gained 116 graduate psychology students
Studied human mind using introspection, a highly practised for of self-examination
His research was conducted in high controlled conditions (experimental methods), which encouraged these researchers such as the behaviourists to follow the same experimental methods (Saul McLeod, October 6 2023)
Germany and Leipzig
The early leaders discussed all worked in Germany as did the Gestalt psychologists
This early leadership in psychology was disrupted by the world wars in the 20th century, and the division of Germany under the Second World War
Leipzig second-oldest university in Germany, and the first in the world to hold a psychological lab, was renamed ‘Karl Marx University’ under the Soviet regime
After reunification of East and West Germany, Leipzig university again flourished
- Leipzig today houses two Max Planck Institutes
- MPI of Evolutionary Anthropology, MPI of Cogntive Brain Sciences
- Brain, cognition and language is one of the University’s six top research areas
20th century vision: the 3 G’s
Extremely exciting time for understanding of vision science
Extensive undertsanding of the neurophysiology of vision from Hubel & Wiesel onwards - but this dissected perception into analysis of fatures/parts
Focus on three important approaches to the psychology of visual perception which have left legacies today
Three different schools of thought
Gestalt psychology
JJ Gibbon’s ecological optics
Richard Gregory’s constructivism
Context: after Wundt
Following a PhD with Wundt, Titchener went to America and established a lab at Cornell in 1892 to pursue structuralism
Using introspection as the method to
- first identify the elements
- then find out how they were combined ir grouped
- by 1896 he had identified 32,820 disctinvire visual sensations
Its was this approach that the Gestalt psychologists challenged
Gestalt psychology
Main protagonists
- Max Wertheimer (1880-1943)
- Kurt Koffka (1886-1941)
- Wolfgang Köhler (1887-1967)
All educated and practising in Germany during WW1
Gstalty psychology developed/flourished 1910-1930 (all moved to US before WW2)
Not just perception -> discussed thinking too
Phi phenomenon
Wertheimer (1912)
A political illusion where stationary objects or lights appear to be moving when displayed in rapid succession, creating a perception of contnous motion. This illusion is based on the principle of persistence of vision, where the brain retains the image of a previous stimulus even after it has disappeared, allowing the net image to appear as a continuation of the previous one (Limeup, 2025)
Marks the start of the Gestalt movement
Cf. Titchener’s structuralism
Focused on identifying th basis building blocks on conscious experience
Introspective analysis of the basic elements of conscious experience
How can this explain how movement is seen, how apparent forms emerge or even ‘squareness’
Said the whole is more than the sum of its parts: sedations, images and affections (G Arnold, January 6 2022)
Examples of Gestalt Laws of perceptual organisation
Proximity
- things that are close together are grouped together
Similarity
- things that look similar are grouped together
Common fate
- things that move together are grouped together
Good continuation
- the spatial Analouge of common fate
- lines move in the way that is the smoothest
The perception of ‘figure’
- closure
- relative sice
- surroundedness
- orientation symmetry
Why do we see in these ways?:
- for Gestalts - reflects ‘field forces in the brain (rather than learning by association’
- this is somewhat ‘nativist’
- more recent thinkers - these ‘laws’ allow us to see natural objets in the same world we have evolved to see. Parts of the same object are more similar, proximate, move together (etc) than of another object or background
- can help explain why camouflage works and how it can be broken
- Extra evidence -
School of thought that emphasises the perception of wholes rather than indivudal parts
Suggests mind organises sensory information into meaningful patterns and structure, and that the whole is greater than the sum of its parts (The Gestalt Centre)
Gestalt is a German word, the closest translation of it being ‘whole’ ‘pattern’ or ‘form’
Holistic perception: - emphasis the idea that we don’t perceive the world as a collection of separate elements, but rather as organised wholes or configurations
Principles of perceptual organisation: - gestalt principles, such as proximity, similarity, continuity, closure, and common fate, explain how we group and organise sensory information to form meaningful perceptions
“The whole is greater than the sum of its parts” - this is a core concept pf Gestatly psychology suggesting the properties of the whole cannot be derived from analysing its individual parts
Emphasis on the present: - gestalt therapy, a form of psychotherapy, focuses on the individual’s expeirnce in the present moment, rather than dwelling on the Past
(Rebecca Mestechkin, 2022)
Other reactions to Titchener: behaviourism and its influence
Roughly the same time as Gestalt period in Germany
Initially radial movement in USA, came to dominate psychology there for almost 50 years
JB Watson (1913) - ‘psychology as the behaviourist views it’
- critical of consciousness as object of study and introspection as a method (cf Wundt et al)
- led to cosndierbale work, mainly of learning, usually in animals, looking for laws of learning how ‘responses’ (behaviour) related ‘stimuli’
Stimulis implied an impoverished input (unlike JJ Gibson)
And ‘behaviourism’ minimised cognitive activities that intervene between ‘S’ and ‘R’ (unliked Richard Gregory)
JJ Gibson’s ecological optics
JJ Gibson 1904-1979
His theory of ‘direct perception’ expressed in three increasingly radical books
- percetoipn of the visual world (1950)
- the senses considered as perceptual systems (1966)
- the ecological approach to visual perception (1979)
Emphasises that the environment provides the information needed for perception, and the perceiver directly “pick up” this information from the ambient optic area
This contrasts with traditional views that see perception as an active cogntive process
Direct perception:
- argued humans perceive their environment directly without the need for complex cogntive processing or mental representations
Ambient optic array:
- propose that the “ambient optic array” is the strcutred arrangement of light in the environment that contains all the information needed for perception
Invariants:
- constant features in ambient optic array, such as tetchier gradients and linear perceptive which provide information about the structure and organisation of the environment
Affordances:
- opportunities or possibilities for interaction that the environment offers to the perceiver
Optic flow:
- the pattern of apparent motion objects, surfaces, and edges caused by relative motion between the observer and the environment
(Online learning college, 2022)
Theory arose from practical problem
During WW2 - how to train pilots quickly
Landing seems to involve depth perception, but training based on depth cues was not effective
Texture gradients in the world surfaces
Dissatisfaction with the ‘depth-cue’ approach led JJ Gibson to re-think how we see the visual world
Optic array, texture gradients and optic flow
Denied roles for ‘representation’ or ‘cognition’
We ‘just see’ the world
E.g. size constancy -> problem goes away when considered a textured ‘ground’ the fallacy of the retinal ‘image’
Richard Gregory’s constructivism
1923-2010
Theory of perception echoes Helmholtz
Fundamental disagreement with the approach taken by Gibson
Gregory’s approach
Emphasise the ambiguity of the perceptual input
Perception as ‘hypotheses’ about what is most likely to have given rise to a particualr retinal input
(For Gibson, no ambiguity where total dynamic array is seen as the input)
- e.g. Muller-Lyer illusion (from R.L Gregory’s Eye and Brain)
Perception is a constructive process that relies on top-down processing
Stimulus information from our environment is frequently ambiguous, so to interpret it, we require higher cognitive information from past experiences or stored knowledge in order to make interference about what we perceive
Perception is a hypothesis which is based on prior knowledge -> we are actively constructing our perception of reality based on our environment and stored information (Saul McLeod, June 16 2023)
Enduring influences
In different ways, these three approached to perception ensure today
Perceptual expeirnce as something that emerges from the interaction of local elements (cf Gestalt, Gibson)
Importance of understanding the ‘stimulus’
Importance of context and expectation
Indivudal differences in perception
