Sensation and Sensation and Perception Chapter 4Perception Chapter 4

Sensation - the stimulation Sensation - the stimulation of sensory receptors and of sensory receptors and the transmission of the transmission of sensory information to the sensory information to the central nervous system.central nervous system.

Sensory receptors are Sensory receptors are located in sensory organs located in sensory organs like the eyes and ears.like the eyes and ears.

Perception - the Perception - the psychological process psychological process through which we interpret through which we interpret sensory stimulation.sensory stimulation.

Absolute Threshold - the Absolute Threshold - the weakest amount of a stimulus weakest amount of a stimulus that can be sensed. (Ex: a that can be sensed. (Ex: a hearing test, the faintest hearing test, the faintest beep you can hear) This is beep you can hear) This is different for everyone. Very different for everyone. Very different in animals.different in animals.

Difference Threshold - the Difference Threshold - the minimum amount of minimum amount of difference that can be difference that can be detected between two detected between two stimuli. (Ex: the difference stimuli. (Ex: the difference between to very similar between to very similar paint chips)paint chips)

Signal-Detection Theory - a Signal-Detection Theory - a method of distinguishing method of distinguishing sensory stimuli that takes into sensory stimuli that takes into account not only their account not only their strengths but also such strengths but also such elements as the setting, your elements as the setting, your physical state, mood etc. physical state, mood etc.

(Ex: your food has little (Ex: your food has little taste when you have a taste when you have a head cold)head cold)

Sensory Adaptation - the Sensory Adaptation - the process by which we become process by which we become more sensitive to weak stimuli more sensitive to weak stimuli and less sensitive to and less sensitive to unchanging stimuli. (Ex: eyes unchanging stimuli. (Ex: eyes adapting to darkness, getting adapting to darkness, getting used to certain sounds)used to certain sounds)

The EyeThe Eye

Pupil - opening in the eye Pupil - opening in the eye that lets in light. The darker that lets in light. The darker it is the more the pupil opens it is the more the pupil opens to let in more light.to let in more light.

Lens - adjusts to the distance Lens - adjusts to the distance of objects by changing its of objects by changing its thickness. thickness.

Retina - sensitive surface that Retina - sensitive surface that acts like film in a camera.acts like film in a camera.Neurons in the eye that are Neurons in the eye that are sensitive to light are called sensitive to light are called photoreceptors. Nerves photoreceptors. Nerves carry visual input to the carry visual input to the brain.brain.

Blind Spot - part of the eye Blind Spot - part of the eye where the optic nerve leaves where the optic nerve leaves the eye. There are no the eye. There are no photoreceptors.photoreceptors.

Rods - photoreceptor that Rods - photoreceptor that allows us to see black and allows us to see black and whitewhite

Cones - photoreceptor that Cones - photoreceptor that allows us to see color.allows us to see color.

Visual Acuity - sharpness of Visual Acuity - sharpness of vision, ability to see details.vision, ability to see details.Nearsighted and farsightedNearsighted and farsighted

The EarThe Ear

Outer Ear, Middle Ear and Outer Ear, Middle Ear and Inner EarInner EarInner EarInner Ear

Cochlea -tube that Cochlea -tube that contains neurons and contains neurons and fluidsfluids

Auditory nerve - transmits Auditory nerve - transmits neural impulses to the neural impulses to the brainbrain

Deafness - about 2 million Deafness - about 2 million Americans are deafAmericans are deafinherited, disease related, inherited, disease related, injury related or old age.injury related or old age.

Conductive Deafness - Conductive Deafness - occurs because of damage occurs because of damage to the middle earto the middle ear

Sensorineural Deafness - Sensorineural Deafness - occurs because of damage occurs because of damage to the inner ear.to the inner ear.

Other SensesOther Senses

SmellSmellOlfactory Nerve - sends info Olfactory Nerve - sends info about odors to the brainabout odors to the brain

Taste - As you get older you Taste - As you get older you may lose your sense of smell may lose your sense of smell which takes away from taste.which takes away from taste.

Skin Senses (Touch)Skin Senses (Touch)Pressure, Temperature, PainPressure, Temperature, Pain

Gate Theory - only a certain Gate Theory - only a certain amount of info can be amount of info can be processed by the nervous processed by the nervous system at a time. system at a time.

This is why if you rub an This is why if you rub an injury it makes it feel injury it makes it feel better because the better because the messages are competing messages are competing for the brain’s attention. for the brain’s attention. The pain message may not The pain message may not be getting to the brain.be getting to the brain.

Many people Many people experience pain in a experience pain in a limb that is no longer limb that is no longer there. More than 1/2 of there. More than 1/2 of veterans with veterans with amputated limbs report amputated limbs report feeling pain. feeling pain.

Body SensesBody SensesVestibular Sense - tells Vestibular Sense - tells you whether you are you whether you are physically upright without physically upright without having to use your eyes.having to use your eyes.

Kinesthesis - the sense Kinesthesis - the sense that informs people about that informs people about the position and motion the position and motion of their bodies.of their bodies.