Process by which the sensory receptors and nervous system receive and represent stimulus energies from our environment
Perception
Process by which the brain organizes and interprets sensory information, transforming it into meaningful objects and events
Bottom-up processing
Analysis that begins with the sensory receptors and works up to the brain's integration of sensory information
Top-down processing
Information processing guided by higher-level mental processes
Draws on one's experiences and expectations
What's Going on Here?
Our sensory and perceptual processes work together to help us sort out complex images, including the hidden couple in Sandro Del-Prete's drawing, The Flowering of Love
Top-down processing
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Transduction
In terms of sensation, it's the process of converting one form of energy into another; such as sights, sounds, and smells, into neural impulses that can be interpreted by an individual's brain
Absolute threshold
Minimum stimulus energy needed to detect a particular stimulus 50 percent of the time
Subliminal
Below an individual's absolute threshold for conscious awareness
Difference threshold
Minimum difference between two stimuli required for detection 50 percent of the time
Just noticeable difference (jnd)
Individuals experience the difference threshold
Weber's law
Principle that two stimuli must differ by a constant minimum percentage to be perceived as different
Weber's law
1lb added to 10lb increased by 10% (JND)
1lb added to 50lb increased only by 2%
for the JND you would need to add 5 lbs to 50 to make 10% (JND)
Subliminal sensation and subliminal persuasion
Individuals can be affected by subliminal sensations which are stimuli that are so weak that people do not consciously notice them
Priming
Activating, unconscious associations in our mind, thus setting us up to perceive, remember, or respond to objects or events in certain ways
Sensory adaptation
Reduced sensitivity in response to constant stimulation
Allows us to focus on changes in our environment
Perceptual set
A set of mental tendencies and assumptions that influence what we perceive
Perceptual set
Fries from McDonald's tastes better in a McDonald's bag than in a plain bag
Light's wavelength
Determines its hue, the color we experience
Light's amplitude
Determines the light's intensity
Visual information processing
Optic nerves connect to the thalamus in the middle of the brain, and the thalamus connects to the visual cortex
Parallel processing
The brain uses parallel processing to allow nerve cells to simultaneously process different aspects
Opponent-process theory
Receptor cells are linked in pairs working in opposition to each other
Red-green
Yellow-blue
Black-white; light/dark
Trichromatic theory
The eye must contain three receptors that are sensitive to red, blue and green colors
Color blindness
Genetic disorder in which people are blind to green or red colors
The Nonvisual Senses
Hearing
Touch
Pain
Taste
Smell
Body Position and Movement
Sound waves
Compressing and expanding air molecules
Sound characteristics
Sound is measured in decibels (dB)
0 dB is the absolute threshold
60 dB is normal conversation
85+ dB: prolonger exposure can cause hearing loss
Touch
Our "sense of touch" is a mix of four distinct skin senses: Pressure, Warmth, Cold, Pain
The Rubber Hand Illusion
Touch perception is affected by expectations and attention
Neural activity is activated even when fake hand is touched or injured
Endorphins
Released in response to pain or rigorous activity
Gate Control Theory
Melzack and Wall (1965, 1983) proposed that our spinal cord contains neurological "gates" that either block pain or allow it to be sensed
Taste
Traditionally, taste sensations consisted of sweet, salty, sour, and bitter tastes. Recently, receptors for a fifth taste have been discovered called "Umami"
Taste is a chemical sense
Each taste bud contains a pore with 50-100 taste receptors, and each react to different types of food molecules and send messages to the brain
Taste is psychological
Perceptual bias can influence taste
Sensory interaction: one sense may influence another
Smell
Like taste, smell is a chemical sense
Smell occurs when molecules in the air reach olfactory receptor cells at the top of each nasal cavity
Smell and memories
The brain region for smell is closely connected with the brain regions involved with memory (limbic system). That is why strong memories are made through the sense of smell
Kinesthesis
The system for sensing the position and movement of individual body parts
Vestibular sense
Located in the inner ear consists of semicircular canals and each deals with different movement: up and down, side to side, tilting from one side to the other
Top-down processing
How do we know that when we hold our finger up to cover the moon they are not actually the same size
What we see is determined by unconscious inferences because our brain seeks logic and order