9 10 14 Psych Chapter 4 Sensation and Perception How the Brain Makes Sense of the World Sensation vs Perception o Sensation The detection of physical energy light sound pressure and chemicals tastes and smells by senses o Perception The brains interpretation of sensory inputs Senses 1 Vision 2 Hearing 3 Chemoreceptors Small and Taste 4 Touch Position Balance Vision energy o Light light contains of photons Photons are discrete units of electromagnetic o Light has wavelengths Visible light makes up just a small part of the electromagnetic spectrum 400 700 nm o Sclera The white of the eye o Iris Colored part of the eye Contracts and expands to control amount of light o Pupil Hole through which light enters the eye o Cornea Covers the pupil and iris o Lens Bends light Changes curvature in response to distance of what you are that enters viewing o Retina The membrane of cells that detect light o Fovea Part of the retina responsible for sharp vision o There are special revision receptor cells called rods and cones o Rods Rods are more common They help us see shape We use then when light is low o Cones Help us to see color o Theories of Vision Trichromatic Theory Opponent Process o Trichromatic Theory Three Types of Cones One most sensitive to red light One most sensitive to green light One most sensitive to blue light o Opponent Processes Three types of vision cell pairs Red vs Green cells Blue vs Yellow cells Black vs White cells Hearing 9 10 14 Psych Hearing is the sense that detects vibrations Sounds travel in a kind of wave called a compression wave Doppler Effect Pitch Refers to how high or low a sound is depends on wavelength Loudness Refers to how much vibration you can detect depends on amplitude Sound enters the ear canal vibrates the eardrum the eardrum vibrates the ossicles stapes incus malleus The ossicles vibrate the cochlea The cochlea contains fluids When the fluid vibrates it bends the cilia of special cells called hair cells Hairs cells send information to the temporal lobe via the auditory nerve Humans can hear a relatively broad range of pitches From 20 to 20 000 Hz How does the brain process such a range Place Theory Says the position of hair cells in the basilar membrane determines whether they re sensitive to high or lower frequencies Explains how we hear between 5000 and 20 000 Hz High frequency Frequency Theory Explains the lowest pitches The rate at which neurons fire reproduces pitch Pitches lower than 100 Hz Volley Theory Sets of neurons fire out of sync at 100 Hz Causes phase locking which allows the perception of medium pitches 100 5000 Hz Infrasound Sound that is too low to hear but can still be perceived It can cause feelings of dread it can make you believe you sense a presence and it can cause visual hallucinations Chemoreception The senses of taste gustation and smell olfaction There are five primary types of taste buds that we know of Salty Sweet Bitter Sour Umami meat Smell We have over 1000 olfactory genes 347 of which code for smell receptors The olfactory lobe is actually part of the brain A chemical is inhaled through the nose attaches to an olfactory receptor and activates the receptor Smell and Emotion Memory The olfactory bulb is located right next to the limbic system which is important for storing long term memories and for emotion o Touch o The Reflex Arc o Body Position We sense pain touch and temperature with free nerve endings in the skin Pain information reaches the brain slower than touch The spinal cord can process touch info before the brain This allows you to stop an injurious behavior before you are aware of pain 9 10 14 Psych In the muscles and tendons there are special cells that let us know where our body is positioned These detect stretch and force Balance Perception o A structure in our ear sends info to the cerebellum Called the semicircular canals they are filled with fluid that bend hair cells as our head moves o Perception is how our brains put sensory info together Our brains actually create a virtual reality out of sensory info Gestalt Principles o Gestalt means whole
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