Sensation

Binding problem: how does sound and light from a stimuli get merged into your mind into one conscious event?

Law Prågnanz: The mind prefers to automatically perceive things in the simplest way (the mind groups things so that we understand. Ex: a smiley face)

Bottom-Up Processing: Noticing the individual aspects and assembling them into a coherent whole

Top-Down Processing: Seeing the whole picture then noticing individual aspects of that perception

Gestalt: produces that the brain/mind follows to automatically, unconsciously organize incoming, afferent (arriving a the brain) sensory information.

Figure-Ground: the brain perceives where the attention is

Phi-Phenomenon: the brain perceives rapidly blinking lights as movement Depth Perception

● MON(ocular)

○ Aural (auditory): Doppler effect (sounds seem louder when they’re closer) ○ Ocular (vision)

■ Relative size: a depth cue whereby objects seem smaller when they’re farther away from the viewer

■ Height in visual field: a depth cue whereby objects that are far away seem to be higher in the field of vision

■ Interposition: a depth cue whereby objects that are closer are in front of things that are further away

■ Linear perspective: a depth cue whereby objects closer to the point at

which two lines appear to converge are perceived as being at a greater

distance

■ Atmospheric cues: the evaporated water in the atmosphere distorted and “blurs” far away objects

■ Texture Gradient: a graduated change in the texture, or grain, of the visual field, whereby objects with finer, less detailed textures are perceived as

more distant (things look smoother that are farther away)

■ Motion Parallax: a depth cue whereby a difference in the apparent rate of movement of different objects provides information about the relative

distance of those objects (closer things look like they’re moving quickly,

faraway things look like they’re moving slowly)

● Bi(nocular)

○ Auditory Disparity (if someone on your right is talking to you, your right ear sends a signal to the brain before the left ear does, but the brain merges these signals. This means you can hear where someone is)

○ Ocular (vision)

■ Retinal disparity: the eye compares two different signals from different eyes and compares the signals to relate the position of the object to the

viewer (the bigger the difference between two signals, the closer the object is)

■ Muscular convergence: the eyes sense the placement of an object by

taking into account the muscle movements of the eyes

Transduction: the process of turning environmental energy, to neural energy, to perception, to thought.

Absolute threshold: the lowest level of a stimulus that we can reliably detect, at least 50% ● Gustav Fechner established this idea

Difference threshold: The smallest possible noticeable difference that the brain can sense. ● Ernst Weber noticed a constant he called k (if you lift 100 pounds, you won’t notice a difference by adding weight unless the weight increases by more than 2%) Just Noticeable Difference: The way humans experience the difference threshold Signal Detection Theory: theory regarding how stimuli are detected under different conditions such as the motivation to notice and the ability to notice.

Sensory adaptation: A reduction of the response of the sensory receptors due to continual exposure

Sensory Habituation: when the brain does not react to certain stimuli after the stimuli has become customary.

Visual Anatomy

Cornea: The transparent part of the coat of the eyeball which covers the iris and pupil and admits light to the interior eye

Iris: the colored sphincter that contracts and relaxes to keep light out or let it in Pupil: the opening of the eye

Lens: is a structure that is stretched by muscles to change the focus of the eye Fovea: the point of central focus of the eye that contains cones (related to color), part of the retina

Retina: the light-sensitive lining of the eye contains rods spread throughout. Allows us to see dim light and motion

Blind Spot: the point at which light does not hit rods or cones, but the image is filled in by the brain

The process of seeing: as light passes through the eye, it hits rods and cones, which sends signals to the bipolar cells, who stimulate the ganglion cells, who relay information to the optic nerve. The optic nerve crosses the brain at the optic chiasm and enters the thalamus before being sent to the cortex of the occipital lobe.

Theories of Color Vision

● Trichromatic theory: there are three types of cells (cones) that respond to different wavelengths of radiation (short = blue, medium = green, long = red). A mix of different signals sent form the cones in different ratios can produce any color. This is supported because it works for the eye’s anatomy and is based on how cones work.

● Opponent Process Theory: when certain neural circuits are excited, they cannot process certain colors because the processes are inhibited (blue vs yellow, red vs green, black vs white). Supported because it works for the brain (explains afterimages)

Sensory Conditions

● Mechanical

○ Deafness

○ Myopia (when the pinpoint image falls short of the fovea, meaning you’re nearsighted)

○ Hyperopia (when the pinpoint image falls to high for the fovea, meaning you’re farsighted)

● Neurological

○ Prosopragnosia: the inability to recognize faces

Perception & Visual Perception

Perceptual Set - a way of perceiving the world based on context, experiences, motivation, and emotions (ex: is # a hashtag or a pound sign? Depends on experience).

● The brain assembles association in a bottom-up process, so it makes a meaning out of different parts of a thing

● Perceptual set is related to top-down (based on previous experience, we put something into a category and work down to finer details)

Phantom Pain - neurons that are placed in association with a lost limb are stimulated, which allow the brain to perceive pain without actually sensing pain.

Placebo Pain - a sugar pill or another substance that is associated with the brain ending perception of pain, though it still senses the pain.

Hallucinations - when the brain perceives a stimulus without the stimulation in the anatomical sensory receptors (i.e. the brain neurons are stimulated so that the brain perceives voices, but the ear does not send any vibrations that would correspond with sound)

Cocktail-Party Effect: explains that organisms can “tune out” certain stimuli when focusing on a specific stimuli, but some unattended messages are being processed, such as one’s name Feature Detectors: Feature detectors are specialized neurons that respond to the components of a visual stimulus, including lines, edges, curves, direction, faces, or color. They do not create a perception or recognition of that stimuli.

Priming: a method used to stimulate a specific unconscious cognitive process in which a person is exposed to information that will later affect the behavior or performance in another task or in another situation.

Perceptions Based on Motivation and Emotion

● When motivated by a certain goal, the brain will perceive more stimuli related to that goal.

● When affected by a certain emotion, the brain will perceive stimuli differently. When there is a good emotion involved, the brain perceives more specifics and vice versa. Waves of Light

● Length of Wave (Frequency)

○ Objective sensation (External): number of waves per unit

○ Type of signal

○ Subjective perception (Internal): Color (short blue, mid green, long red) ● Height of Wave (Amplitude)

○ Objective sensation (External): Amplitude

○ Intensity of Signal

○ Subjective perception (Internal): Brightness

Perceptual Constancies

● Size Constancy: the ability to retain the size of an object regardless of where it is located, in memory

● Color Constancy: the ability to perceive an object as the same color regardless of the environment. This constancy only works when the brain already recognizes the specific color.

● Shape Constancy: the ability to perceive an object as having the same shape regardless of the angle. (ex: a half open door is perceived as a rectangle, even though the stimulus is a trapezoid)

● Brightness Constancy: the ability to keep an object's brightness constant as the object is moved to various environments

Task Switching: the brain cannot perform two tasks at the same time. While the brain may be sensing multiple things at once, the brain only perceives one task or stimulus. Inattentional Blindness: when the brain still receives certain stimuli, but a lack of attention to that stimuli in the brain leads the brain to not perceive that stimuli.

Subliminal Perception: Perception below the threshold of awareness

● Mere exposure effect: the more the brain receives a certain stimuli, the more likely you are to enjoy or remember that stimuli.

● Context Effect: describes the influence of environmental factors on one's perception of a stimulus

● Context Clues: directions or instructions that the brain uses to make sense of confusing or ambiguous sensations.

Neurological Illusions: the brain receives a certain stimuli, but distorts the perception of that stimuli based on gestalt cues, perceptual sets, or the top-down process

Stroboscopic Effect (Phi Phenomenon): illusion of apparent movement that results from flashing a series of still pictures in rapid succession; the brain merges these images together to create the idea of movement.

Auditory Sensation

Transduction: environmental energy to neural energy to perception

What Happens with Vibrations (3 Variables)

● Length of Wave (Frequency)

○ Objective sensation (External): Number of waves per unit (Hertz)

○ Type of signal

○ Subjective perception (Internal): Pitch

● Height of Wave (Amplitude)

○ Objective sensation (External): Amplitude (decibels)

○ Intensity of Signal

○ Subjective perception (Internal): Loudness

● Shape of Wave (Purity)

○ Objective sensation (External): Purity

○ Which instrument is being played

○ Subjective perception (Internal): Timbre (example: a violin and a tuba play the same note (frequency) at the same loudness (amplitude), but it sounds different) Anatomical Process of Hearing

● Pinna - Outer ear, gathers sound

● Tympanic membrane - eardrum amplifies vibrations

● Hammer (malleus) - vibrates with sound and hits anvil

● Anvil (incus) - vibrates after the anvil hits it and stimulates stirrup

● Stirrup (stapes) - vibrates and hits the cochlea at the oval window and sends vibrations through the cochlear fluid

● The basilar membrane of the cochlea contains hair cells connected to neurons. When the hair vibrates, that energy is transferred to nerves carried by the auditory nerve to the brain.

Other Senses

Vestibular System - the awareness of where the head is in relation to the ground ● 3 dimensions: nod, shake, and twist

● 3 semicircular canals (strongly related to balance!)

○ On the cochlea

○ As the fluid in these shifts and hits certain receptors; we perceive this as where our head is in space

● Motion sickness is when signals from the vestibular system in the ear and the signals from your eyes clash, resulting in nausea or dizziness.

● Proprioception - awareness of where parts of your body are

● Kinesthesia - awareness of what body parts are doing, including how fast they are moving and in which direction of

Somatic & Tactile Senses - touch

● Very subjective (tickling is subjective, some people think some things are hot but others think it’s fine)

● Gate Control Theory - pain signals (afferent) coming from nociceptors (pain neurons all over the body) from PNS to CNS can be blocked from entering the CNS at the spinal cord

○ If you have a mosquito bite and the itchiness signal needs to go to your CNS, but that has a lot to do, so pressure, cold, and heat keep it from entering the CNS because it’s focusing on those other things.

Taste (Gustation)

● Sweet, salty, sour, bitter, umami (savory)

● What we think we taste just fits into several of these categories at once ● You have all types of taste receptors all over your tongue

● Taste is subjective and can be influenced by expectation, culture, and emotions Smell (Olfaction)

● Certain inhaled molecules excite certain receptors (not a 1:1 relationship - fake example, there isn’t a mocha receptor, it’s a chocolate and a coffee combined)

● Smell bypasses the thalamus, but it is strongly connected to emotion centers ● Pheromones: subtle unconscious odors from our bodies.