Review Session 3: Sensation and Perception

What is Sensation? Senses: systems that translate information from outside of our nervous system into neural activity. Sensations: Messages from the senses that are interpreted in the brain (perception) and impact our behaviors.

The Process of Sensation: There are 5 distinct processes that take place in sensation

Problems with Coding: DEF: The translation of the physical properties of a stimulus into a pattern of neural activity that specifically identifies those properties. -Specific Nerve Energies: specific stimuli can only be encoded by specific senses -Temporal Codes: Codes that deal with timing of neural activity -Spatial Codes: Codes that deal with location of neural activity

Hearing: Our sense that picks up on the sounds around us The accessory structure for this sense is our ear.

Deafness: A person who cannot hear is termed “deaf” -Conduction Deafness: deafness that occurs when the 3 small bones in the middle ear fuse and no longer vibrate correctly -Nerve Deafness: When damage occurs to the auditory nerve resulting in loss of hearing (much more rare)

Laws of Sound: Frequency: The number of complete wavelengths that pass by a given point in space every second Loudness: A psychological dimension of sound determined by the amplitude of a sound wave Pitch: How high or low a tone sounds Timbre: The mixture of frequency and amplitude that determines the quality of a sound

Vision: Our sense that picks up on light around us The accessory structure for this sense is our eye.

Visible Light and Intensity: The light we can sense must fall within the visible spectrum (Between 400 nanometers in wavelength to a 750 nanometers of wavelength) Light intensity (How much energy light contains) must also be enough to be sensed.

Rods and Cones: Rods are specialized cells that allow us to pick up the intensity of light This is where our photoreceptors are located Cones allow us to sense the color of something This is where our photopigments are located

Optic Pathways: The encoded messages from our eyes travel to the optic nerve From there the nerves cross in the optic chiasm Next, the information moves to the thalamus Finally, perception occurs within the Occipital Lobe (Primary Visual Cortex).

Seeing in Color: Hue: determined by wavelength of light. Saturation: purity of a color Brightness: intensity of the light Trichromatic Theory: all color is a composite of red, green, and blue Opponent –Process Theory: all color is red-green, blue-yellow, or black-white. These pairs offset each other.

Olfaction and Gustation: Olfaction: Smell (goes directly to the thalamus w/out coding)(accessed by nose) Gustation: Taste (Accessed by taste buds) These are connected

Somatic Senses: Def: Senses related to our sense of touch or feel -Texture -Pain -Temperature -Kinesthesia: where and what your body parts are doing at any time.

Vestibular Sense: DEF: Our sense of balance -Located within our ear

Synesthesia: DEF: When our senses become mixed together -Can make it incredibly difficult to sense what is really occurring in the world around us.

What is Perception? DEF: The process through which people take raw sensations from the environment and interpret them, using knowledge, experience, and understanding of the world so that sensations become meaningful experiences

Computational Approach: Def: An approach to perception that focuses on how computations by the nervous system translate raw sensory stimulation into an experience of reality. -EX: We see hear a sound that we are not familiar with, but our Auditory Cortex attempts to infer what it is.

Constructivist Approach: DEF: An approach to perception in which fragments of information from our senses is constructed into reality. EX: A mountain is behind a cloud. Our brain will make up the rest of the information.

Ecological Approach: DEF: an approach to perception in which people are adapted to their environment, so they do not need to use complex thinking to perceive sensory input. EX: I hear a man’s voice. I do not need to see him to know he’s a man.

Weber’s Law: DEF: Law of perception stating that the smallest detectable difference in stimulus energy is a constant fraction of the intensity of the stimulus EX: If I was carrying a bucket full of water that weighed 25 pound, how much would need to be added for me to notice a difference? This would be represented using a fraction.

Perceptual Organization: DEF: The process of determining what edges and other stimulus form an object

Perception of Location and Distance: Depth Perception: The ability to perceive distance Relative Size: A depth cue where larger objects are perceived as closer than smaller objects

Perceptual Constancy: DEF: The perception of objects as constant in size, shape, color, and other properties despite changes in their retinal image EX: If my friend is ¼ mile away, they are still 6’ 2” even though they look smaller.

Bottom Up Processing:

Top Down Processing:

Attention: