What is the difference between sensation and perception?
Sensation is the transduction of physical stimulation into neural signals; perception is the interpretation of that input into a meaningful subjective experience.
What is psychophysics?
The scientific study of the relationship between physical stimulus properties and subjective perceptual experience.
What does Fechner’s Law state?
The increase in stimulus intensity required to detect a change is proportional to the original stimulus intensity.
What is contrast in vision?
The difference in luminance between adjacent elements in a scene.
What is spatial frequency?
The amount of detail in an image, measured as variation in contrast per unit of visual space.
At what spatial frequency are humans maximally sensitive?
Approximately 5–8 cycles per degree of visual angle.
What is the maximum spatial frequency visible to humans?
Roughly 60 cycles per degree of visual angle.
What does orientation tuning in V1 refer to?
Neurons in V1 respond preferentially to edges or bars at specific orientations.
What is binocular disparity?
The difference in images between the two eyes used as a cue for depth perception.
Why is human vision considered trichromatic?
Because we have three types of cones sensitive to different wavelengths (short, medium, long).
Where are cones concentrated in the retina?
In the fovea.
What is colour constancy?
The tendency to perceive an object’s color as stable despite changes in illumination.
What is bottom-up processing?
Data-driven processing that begins with sensory input and builds toward higher-level interpretation.
What is top-down processing?
Concept-driven processing influenced by prior knowledge, expectations, and context.
What did Phelps et al. (2006) show about emotion and perception?
Fearful stimuli enhance contrast sensitivity compared to neutral stimuli.
What is the Gestalt principle of proximity?
Elements that are close together are perceived as belonging together.
What is the Gestalt principle of closure?
We tend to perceive incomplete figures as complete.
What is figure-ground segmentation?
The perceptual separation of an object (figure) from its background (ground).
What is denotivity in figure-ground perception?
Familiar and meaningful shapes are more likely to be perceived as the figure.
What are the two visual streams after V1?
The ventral ‘what’ pathway and the dorsal ‘where/how’ pathway.
What is the function of the ventral stream?
Object identification, including shape and texture processing.
What is the function of the dorsal stream?
Guiding action using spatial information.
What does a double dissociation between DF and VK demonstrate?
That object recognition (ventral) and visually guided action (dorsal) rely on distinct neural systems.
What is visual agnosia?
An inability to identify or recognize visual objects despite intact basic vision.
