Chapter 3: Sensation and Perception

Sensory receptors collect information from the environment and send it to the brain, which processes it to make sense of what's happening.

Bottom-up processing

This process starts in the brain. When we already have an idea of what's happening, it can shape how we understand new information.

Top-Down Processing

What is the main purpose of Sensation and Perception?

Adaptation to help with survival.

Specialized cells that detect stimulus information and transmit it to sensory nerves.

Sensory Receptors

How do sensory neurons communicate intensity?

Intensity is communicated by the frequency of action potentials (how often the neurons fire).

A rare condition where stimulating one sense causes a person to have an experience in another sense. Ex. seeing colors when hearing music or tasting flavors when seeing certain shapes.

Synaesthesia

The minimum amount of stimulus energy that a person can detect, which is the threshold where a subject detects something correctly 50% of the time.

Absolute threshold

The smallest amount by which two sensory stimuli can differ in order for an individual to perceive them as different.

Difference threshold

This refers to the brain's ability to detect and respond to information even when you're not consciously aware of it

Subliminal Perception

Focusing on a particular aspect of something and ignoring other things. The process of choosing what to focus on.

Selective attention

An example of selective attention where you pay attention to one particular voice that mentions your name or something you are interested in amidst other conversations.

Cocktail Party Effect

Happens when your attention is focused so much on one thing that you fail to notice other things, even if they’re important or obvious.

Inattentional bias

When your brain is ready to see or understand things in a certain way based on your past experiences, expectations, or emotions.

Perceptual Set

When your senses get used to something and stop noticing it after a while. Ex. eyes adjusting to a dark room or habituating to a ticking clock.

Sensory Adaptation

What are the three properties of light waves and what do they determine?

Wavelength determines color, amplitude determines brightness, and purity determines saturation or richness of color.

White, outer part of the eye.

Sclera

The colored part of the eye containing muscles that control the size of the pupil.

Iris

Black opening at the center of the Iris

Pupil

Clear membrane at the front of the eye.

Cornea

A transparent disk-like structure that, along with the cornea, bends light to the focal point at the rear of the eye.

Lens

The light-sensitive surface at the rear of the eye that records electromagnetic energy and converts it to neural impulses, containing 126 million receptor cells.

Retina

Receptors in the retina that function well in little light, numbering approximately 120 million.

Rods

Receptors in the retina used for color perception, numbering approximately 6 million.

Cones

A tiny point on the rear of the retina where vision is best and contains only cones, where inputs are directed.

Fovea

Axons of the ganglion cells that transmit visual information from the eye to the brain for processing.

Optic Nerve

The area where the optic nerve leaves the eye, containing no rods or cones.

Blind Spot

What is Parallel Processing in the visual system?

Multiple levels of processing, such as shape, color, and density, occurring at the same time in the visual cortex.

What is Binding in visual processing?

Bringing together information that is processed in different neural pathways to form a coherent perception.

What is the Trichromatic theory of color vision?

The theory that color perception is produced by three types of cone receptors sensitive to green, red, and blue light.

What is the Opponent Process theory of color vision?

The theory of color perception that produces afterimages, involving opposing pairs like red-green and blue-yellow.

The perceptual ability to distinguish and separate a prominent object (the figure) from its surrounding environment (the ground or background) in a visual scene

Figure-Ground

A school of thought emphasizing that the mind perceives things as a unified whole rather than as separate parts, based on principles like Closure, Proximity, and Similarity.

Gestalt Psychology

The ability to perceive the three-dimensional (3D) structure of the world, including the distance between objects and their relative positions in space.

Depth Perception

Your brain uses this to judge distance by using both of your eyes to form images.

Binocular Cues

A binocular cue indicating how close or far something is based on the degree to which the eyes turn inward to focus on an object.

Convergence

Visual depth cues that can be perceived by one eye alone. Familiar sizes and shapes, height in a field of view, linear perspective, overlap, shading, texture gradient.

Monocular Cues

Key to survival as predator or prey. Specialized neurons to detect motion.

Motion Perception

The idea that we recognize objects as constant and unchanging (e.g., in size, shape, or color) even though the sensory information about them may change.

Perceptual Constancy

The phenomenon where we perceive objects to have a stable size, even as the size of their image on our retina changes with distance.

Size Constancy

The perceptual phenomenon where an object’s shape is perceived as consistent even as its retinal image changes due to different angles or orientations.

Shape Constancy

Idea that color stays the same even though different light levels may fall on it.

Color Constancy

What is the relationship between wavelength, frequency, and pitch in sound?

A sound wave's wavelength determines its frequency, and frequency is perceived as pitch (high frequency as high pitch, low frequency as low pitch).

The outer part of the ear that collects sounds and channels them to the interior of the ear.

Pinna

What are the components of the middle ear and what is their function?

The eardrum, hammer, anvil, and stirrup, which channel and amplify sound as it prepares to enter the fluid portion of the inner ear.

What are the key structures of the inner ear and their function?

The oval window, cochlea, and basilar membrane, which convert sound waves into neural impulses.

The theory that different frequencies produce vibrations at particular places on the basilar membrane, explaining how high-frequency sounds better.

Place Theory of Hearing

The theory that the perception of frequency depends on how often the auditory nerve fires.

Frequency Theory

A concept in auditory science that explains how the brain perceives sound frequencies higher than what a single neuron can process

The Volley Principle

How does the brain localize (pinpoint) sound?

By processing and combining slightly different sensory information (timing and intensity variations) received by the two ears.

What are the three main skin senses?

Touch, Temperature, and Pain.

How is smell unusual among the senses in terms of brain processing?

It doesn't go through the thalamus but directly to the olfactory areas in the temporal lobes, creating strong links to emotion and memory in the limbic system.

The sense that provides information about movement, posture, and orientation, with receptors embedded in muscle fibers and joints.

Kinesthetic Sense

What is the Vestibular sense?

The sense that provides information about balance and movement, detecting head motion via sensory receptors in the semicircular canals of the inner ear.