Sensation and Perception Flashcards
(80 cards)
Distinction Between Physical and Perceptual
Physical: Actual external stimuli.
Perceptual: Individual interpretation of stimuli.
Example: Misidentifying sounds or images due to expectation or context.
Seven Steps of the Perceptual Process:
Seven steps, plus “knowledge” inside the person’s brain, describe the process of perception.
These steps occur between the time a person looks at the stimulus in the environment (e.g., a tree), perceives the stimulus, recognizes it, and takes action toward it
Distal Stimulus
Proximal Stimulus
Receptor Processes
Neural Processing
Perception
Recognition
Action
Distal Stimulus
Object in the environment. Observer selectively attends to objects.
Proximal Stimulus
The representation of the distal stimulus on the receptors.
Stimulus is “in proximity” to the receptors Image on sensory receptors.
Receptor Processes
Sensory receptors are cells specialized to respond to environmental energy.
Visual pigment is what reacts to light.
Transduction occurs, which changes environmental energy to nerve impulses.
The end result is an electrical representation of the tree.
Neural Processing
Signals are transmitted and processed in the brain.
Neural processing - changes that occur as signals are transmitted through the maze of neurons
Primary receiving area
Occipital lobe
Temporal lobe
Parietal lobe
Perception
Awareness of stimulus.
Recognition
Categorization of stimulus.
Action
Response to stimulus.
Top-Down vs. Bottom-Up Processing
Bottom-Up (Data-Driven): Processing based on incoming stimuli from the environment
Top-Down (Knowledge-Based): Influenced by prior knowledge and expectations.
Absolute Threshold
the smallest amount of energy needed to detect a stimulus
Difference Threshold
The smallest detectable difference between two stimuli that a person can define
Principles of Transformation and Transduction
Transformation: When the stimuli and responses created by stimuli are transformed, or changed, between the environmental stimuli and perception.
Transduction converts environmental energy into electrical signals.
Magnitude Estimation
How perceived stimulus intensity does not always match actual intensity.
Perceptual World
Relationship between stimuli and perception above the threshold.
Method of Limits
Vary level of stimulus from low to high or reverse and note at what point the subject changes from detecting something to not, then switch directions. Average over many trials to determine threshold.
Method of Adjustment
Continuous adjustment of stimulus intensity.
Method of Constant Stimuli
Randomized stimulus levels to determine 50% detection rate.
Step 1and 2 of the Perceptual Process Explanation
Step1: Information about the tree (the distal stimulus) is carried by light.
Step 2: The light is transformed when it is reflected from the tree, when it travels through the atmosphere, and when it is focused on by the eye’s optical system. The result is the proximal stimulus, the image of the tree on the retina, which is a representation of the tree.
Specificity Coding
A specialized neuron that responds only to one concept or stimulus (e.g., “the grandmother cell”)
Sparse Coding
Small groups of neurons respond to stimuli.
Occurs when a particular stimulus is represented by a pattern of firing of only a small group of neurons.
Population Coding:
Large patterns of neuron activity represent stimuli.
Proposes that our experiences are represented by the pattern of firing across a large number of neurons.
Electrical Signals in Neurons
Action potentials are brief electrical signals lasting ~1 millisecond.
Remain constant in size, with increased stimulus intensity causing higher firing rates.
Synaptic Transmission
Neurotransmitters bridge the gap between neurons, fitting specific receptor sites.
