Presentation is loading. Please wait.

Presentation is loading. Please wait.

Sensation and Perception

Similar presentations

Presentation on theme: "Sensation and Perception"— Presentation transcript:

1 Sensation and Perception
Module 9 & 10 Sensation and Perception

2 ThEcOwgAvecOla. The cow gave cola

3 The cat saw the rat. The cat was the rat.
.rat eht saw tac ehT The cat saw the rat. The cat was the rat.

4 Absolute Thresholds The level of sensory stimulation necessary for sensation to occur. Vision: Candle flame seen at 30 miles on a clear night. Hearing: Tick of a watch under quiet conditions at 20 feet Touch: A bee’s wing falling on you cheek from 1 centimeter (.4 inch) above. Smell: 1 drop of perfume diffused into a three room apartment Taste: 1 teaspoon of sugar in 2 gallons of water.

5 Difference Threshold The minimum difference that a person can detect between two stimuli. Just noticeable difference

6 Signal Detection Theory
Set of formulas and principles that predict when we will detect the presence of a faint stimulus amid background stimulation. Detection depends on qualities of the stimulus, the environment, and the person who is detecting. Three Variables: Stimulus Variable: how bright is the blip on the radar screen Environmental Variables: how much distracting noise is there in the room with the radar equipment Organismic Variables: is the operator properly trained and motivated.

7 Diminished sensitivity as a result of constant simulation.
Sensory Adaptation Diminished sensitivity as a result of constant simulation.

8 Selective Attention Focusing conscious awareness on a particular stimulus to the exclusion of others.


10 The process of receiving information from the environment.
Sensation The process of receiving information from the environment.

11 Vision Dominates human senses. Light
White Light: light as it originates from the sun or a bulb before it is broken into different frequencies. Color is seen because light bounces off objects at different frequencies. The eye has different receptors for different wave lengths. Wave lengths are based on the texture and solidity of what they hit.

12 Electromagnetic Energy
An energy spectrum that includes X-rays, radar, and radio waves, among other things. A small portion of this spectrum includes visible light energy, which can be detected by the eye. Two Characteristics Determines What We See: Length of the wave determines color Hue: The color of light, determined by the wavelength of light energy Amplitude of the wave (height) determines brightness Taller is brighter.


14 Parts of the Eye Cornea: clear outer covering of the eye, behind which is a fluid. Iris: a colored circular muscle that opens and closes, forming larger and smaller circles to control the amount of light getting into the eye. Lens: the part of the eye that focuses an image on the retina.

15 Parts of the Eye Pupil: The opening in the eye.
Psychological factors that control iris muscles. Smaller when disgusted Larger when Really like something or someone Afraid Strong emotional arousal Retina: Back of the eye, which contains millions of receptors for light.


17 Parts of the Eye Rods: A visual receptor most sensitive to violet-purple wave length; very sensitive for nigh vision; “sees” only black and white. Cones: a visual receptor that responds during daylight; “”sees” color. Red range Rods are on the side and cones in the middle of the retina.

18 Differences Between the Cone and Rod Receptors
Cones Rods Number 6 million Location in Retina Center (fovea) Color Sensitive? Yes Sensitivity I dim light? Low Ability to detect sharp detail (acuity)? High Number 120 million Location in Retina Edge (periphery) Color Sensitive? No Sensitivity in dim Light? High Ability to detect sharp detail (acuity)? Low

19 Rods and Cones Bipolar Cells: cells that form the middle layer in the retina. Bipolar cells gather information from the rods and cones and pass it on to the ganglion cells. Ganglion Cells: the top layer in the retina. Ganglion cells receive information from the bipolar cells and transmit it through their axon, which together form the optic nerve. Optic Nerve: the nerve that carries visual information from the eye to the occipital lobes of the brain. Blind Spot: the point at which the optic nerve travels through the retina to exit the eye. The lack of receptor rods and cones at this point creates a small blind spot.

20 Color Blindness Inability to perceive certain colors, such as red and green. 8% Males .05 % Females Red and Green cones do not work Truly color blind people are very rare

21 Afterimage Image that remains after stimulation of the retina has ended. Cones not used fire to bring the visual system back in balance.

22 Audition: the sense of hearing.

23 Characteristics of Sound
Pitch: How high or low a sound is Timbre: the complexity of a sound Intensity: how loud a sound is Decibels: a measure of how loud a sound is (its intensity)

24 The Structure of the Ear
Eardrum: a piece of skin stretched over the entrance to the ear; vibrates sound Cochlea: A snail-shaped part of the ear, filled with fluid and small hairs that vibrate to incoming sound Hair-cells: receptor cells for hearing found in the cochlea Cilia: Hairlike extensions on cells Auditory nerve: bundle of nerves carrying sound to the brain


26 Hearing Sound waves go to the eardrum where vibration is started. This vibration causes the cochlea to vibrate where cilia are located. Cilia are tuned to receive different frequency movements of hare that cause electrical impulses to go through the auditory nerve to the brain. How strong and when a sound arrives at one ear is contrasted by the brain with the same thing from the other ear. Difference help us locate where sound is coming from

27 Cutaneous Senses ( Touch)
Cutaneous Receptors: Nerve receptors in the skin that respond to pressure, temperature, or pain Records pressure Changes in temperature Remain active continuously to record an injury or poison Can fire for hours and hours after accidents

28 Smell Olfaction: the sense of smell
Odor is hard to explain in words but when associated with emotional events. We never forget it. Odor can recreate strong emotional memories. Olfactory Bulb: units that receive odor molecules and communicate their nature to the brain

29 Smell Cilia in the nose collect molecules of odor which send and electrical impulse to the olfactory bulb which generates a “code” that is sent to the brain for interpretation. Smell is most critical in eating. More than taste Pheromones: odor chemicals that communicate a message Animals have them. Not sure if humans do.


31 Taste Taste receptors: chemical receptors on the tongue that decode molecules of food or drinks to identify them Types Salt Sweet Sour Bitter Work the same as cones

32 Salt Necessary for survival
Operates nerve cells Keeps body chemistry in balance Used for muscle contraction Children crave salt and it tampers with age until really old it re-opens

33 Sugar (sweet) Necessary for energy Newborns can taste at one day old
Too little sugar makes a person tremble, feel faint, and causes mental confusion The desire for something sweet is built in

34 Sourness and Bitterness Detectors
Bitterness - Poisons - no odor Sourness - Food gone bad - odor

35 Body Senses Kinesthetic sense: the system for sensing the position and movement of individual body parts. Vestibular sense: the system for sensing body orientation and balance, located in semicircular canals of the inner ear.

36 Perception The process of organizing and interpreting sensory information Bottom-up process: Information processing that focuses on the raw material entering through our eyes, ears, and other organs of sensation. Top-up Process: Information processing that focuses on other expectations and experiences I interpreting incoming sensory information

37 Gestalt The “whole,” or the organizational patterns, that we tend to perceive. The Gestalt psychologists emphasized that the whole is greater than the sum of its parts.


39 Figure-Ground Relationships
Figure-ground: the organization of the visual field into objects that stand out from their surroundings.


41 Grouping Principles: the perceptual tendency to organize stimuli into understandable groups
Similarity: a perceptual cue that involves grouping like thins together Proximity: a perceptual cue that involves grouping together things that are near one another Closure: the process of filling in the missing details of what is viewed


43 The ability to see in three dimensions and judge distance
Depth Perception The ability to see in three dimensions and judge distance

44 Example: Visual Cliff: an apparatus used to demonstrate depth perception

45 Binocular Depth Cues: depth cues that require the use of both eyes
Retinal Disparity: The difference between the image provided by the two retinas When the images are brought together in the brain, they provide the sense of depth Convergence: the tension in the eye muscles when the eyes track inward to focus on objects close to the viewer Short distance

46 Monocular Depth Cues: Depth cues that require the use of only one eye
Relative Size: If an object of known size appears large, it is probably close, and if an object appears small, it is probably distant Relative Motion: Apparent slowness indicates an object is distant Interposition: Closer objects partially obstruct the view of more distant objects Relative Height: distant objects appear higher in a your field of vision that closer objects do

47 Monocular Depth Cues Texture Gradient: how rough or smooth objects appear Gradient: Different level of textures we can see at different distances Relative Clarity: Distant objects are less clear than near by objects are Linear Perspective: Parallel lines seem to draw together in the distance

48 Motion Perception Stoboscopic motion Phi phenomenon

49 Perceptual Constancies: perceiving the size, shape , and lightness of an object as unchanging, even as the retinal image of the object changes. Size Constancy: the ability to retain the size of an object regardless of where it is located. Shape Constancy: The ability to perceive an object as having the same shape regardless of the angle at which it is seen Lightness Constancy: The ability to see an object as having a constant level of lightness no matter how the lighting conditions change

50 A mental predisposition to perceive something one way and not another
Perceptual Set A mental predisposition to perceive something one way and not another Schemas: concepts or mental frameworks that organize and interpret information


52 The setting or environment in which we interpret sensory stimuli
Context The setting or environment in which we interpret sensory stimuli

53 In accurate perception
Illusions In accurate perception



Download ppt "Sensation and Perception"

Similar presentations

Ads by Google