Scott-Samuel: Visual perception Flashcards
Lecture 1- What are the four main forms of constancies in vision?
Size, light, colour, and shape.
And the important thing to know about constancies is that its all about context, our perception of size, colour, light and shape is skewed by the surroundings
Lecture 1-
Cone vs. Rod cells
cone- Responsible for central vision, colour vision, and functioning in well-lit conditions.
rod- Responsible for peripheral vision and seeing in dim light; they cannot detect colour.
Lecture 1- What is the function of retinal ganglion cells?
Detect edges, lines, and changes using their receptive fields.
Lecture 1: What are the two types of retinal ganglion cells, and how do they differ?
Parvocellular cells: Larger cell bodies, larger receptive fields, colour-sensitive, found in the fovea, and have prolonged responses.
Magnocellular cells: Not colour-sensitive, distributed throughout the retina, and have transient responses.
Lecture 1: Q: What is the role of the lateral geniculate nucleus (LGN)?
Acts as a filter between the retina and primary visual cortex (V1), reducing signals to avoid overwhelming the brain.
Lecture 1: Where is the primary visual cortex (V1) located, and what does it detect?
Located at the back of the head; it detects oriented edges and bars, their movements, and their ends.
Lecture 1: What are the three types of cells in the primary visual cortex, and how do they differ?
Simple cells: Detect specific orientations, bar widths, and are fixed in location.
Complex cells: Larger, detect moving stimuli, and have no fixed location.
Hyper-complex cells: Similar to complex cells but have inhibitory ends that prevent signals from passing if the stimuli are too large or move in the wrong direction.
Lecture 1: What are the two visual streams, and what do they detect?
Ventral (temporal) stream: Detects “what” (objects, shapes, and identities).
Dorsal (parietal) stream: Detects “where” (location and motion).
Lecture 2- What are canonical views in the context of visual perception?
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Canonical views refer to the perspective that we find it much harder to interpret visual input that is not from our own point of view. Essentially, we tend to understand and process visual information better when it matches the viewpoint we are accustomed to.
Lecture 2- How does modularity relate to the visual cortex and brain function?
Modularity refers to the idea that certain brain areas are specialized for specific functions. For example, the Fusiform Face Area (FFA) is thought to activate for face recognition. However, this concept is challenged by findings that some areas may be more flexible and dedicated to tasks that require expertise, rather than strictly being domain-specific.
Lecture 2- What is multiplexing in the context of visual processing?
Multiplexing refers to the idea that neurons in the brain can carry out multiple functions simultaneously. In vision, groups of simple cells can distinguish different aspects of visual input, allowing for more efficient processing of complex stimuli
Lecture 2- What is plasticity in the brain, and how does it relate to sensory input changes?
Plasticity refers to the ability of neuronal maps to change and adapt over time. This can be seen in cases such as when someone loses a limb through amputation, which can lead to altered sensory input and phenomena like phantom pain, demonstrating the brain’s adaptability to changes in the body.
Lecture 2- Why is vision considered the ultimate sense?
Vision is considered the ultimate sense because it provides the most detailed and reliable information about our surroundings, surpassing many other senses. This is why techniques like mirror boxes are effective in easing phantom limb pain—by “seeing” the limb, the brain receives visual feedback, which helps reduce the sensation of pain.
Lecture 2-
What is the state of research on attention, especially in vision?
Q6: Research on attention is vast but often vague and ill-defined, with no general consensus on its exact nature. However, it is widely accepted that attention plays a significant role in vision, as it helps us focus on important visual stimuli in our environment.
Lecture 2- Why are illusions important in the study of vision psychology?
Illusions are important because they reveal the limitations or failures of our visual system, providing insight into how the brain processes visual information. By studying illusions, researchers can better understand the mechanisms behind vision and perception.
Lecture 2- Why do many visual illusions occur?
Many visual illusions occur because we make assumptions about the distance of objects (whether they are closer or further away), which affects our perception of their size. Additionally, the context or surrounding objects can alter how we interpret the target object.
Lecture 2-
hit me with some illusions
Some well-known visual illusions include:
The moon illusion
The Muller-Lyer illusion
Shepard’s table
The vertical-horizontal illusion
The Titchener/Ebbinghaus illusion
Bistability illusions
Lecture 2-
How does the brain approach visual processing? Main take away from all this illusion research
Vision doesn’t work as a passive “viewer” of the world. Instead, the brain actively investigates the surroundings, using clues and context to determine the most likely interpretation of what is being seen.
Lecture 3-
What is the trichromatic theory of colour vision?
The trichromatic theory states that we have three different types of receptors for three different colours, which is supported by the presence of three different cone cells in the retina
Lecture 3- What limitation of the trichromatic theory does the opponent-processing theory address?
The trichromatic theory does not explain why colour blindness occurs in pairs (e.g., red-green) or why we experience afterimages in four different colours. The opponent-processing theory accounts for this by proposing two types of colour-opponent cells: red-green and blue-yellow, along with a light-dark system.
Lecture 3- How do the trichromatic and opponent-processing theories work together?
The two theories operate at different levels of processing. Trichromatic theory applies to retinal processing, while higher-level visual processing follows the opponent-processing model.
Lecture 3-Why has colour vision evolved?
Colour vision has evolved to help us forage for food, select mates, and avoid diseased individuals.
Lecture 3- What is binocular disparity, and how does it contribute to depth perception?
Binocular disparity refers to the slight difference between the images seen by each eye due to their distinct yet overlapping fields of vision. This difference allows the brain to calculate depth through a process called stereopsis.
Lecture 3-How does research on individuals with one eye inform our understanding of depth perception?
Studies show that people with only one eye can still perform depth-related tasks, such as picking blackberries, at similar levels to those with two eyes. However, they tend to get more scratches, suggesting that their close-range depth perception is impaired.
