Introduction to psychology
Chapter 5: Sensation and Perception
Synesthesia: the production of a sense impression relating to one’s sense or body part by
stimulation of another sense or body part.
5.1 How Does Perception Emerge from Sensation?
LEARNING OBJECTIVES:
Distinguish between sensation and perception.
Describe how sensory information is translated into meaningful stimuli.
Explain the concept of threshold. Distinguish between absolute threshold and
difference threshold.
Explain how thresholds are related to signal detection and sensory adaption.
Sensation: the detection of external stimuli and the transmission of this information
to the brain.
Perception: the brain’s further processing, organization, and interpretation of
sensory signals/information.
Sensation = detection
Perception = construction
- Stimulus sensation sensory coding perception
Experience guides sensation and perception, but sensation and perception are also
integrated into experience.
Bottom-up Processing: perception based on the physical features of the stimulus.
Top-down Processing: how knowledge, expectations, or past experiences shape the
interpretation of sensory information.
Context affects perception.
What makes proofreading our own work so difficult.
Sensory Information Is Translated into Meaningful Signals
Sensory Coding: the process of sensory systems translating the physical properties of stimuli
into patterns of neural impulses.
, Transduction: the process by which sensory stimuli are converted to signals the brain
can interpret.
Sensory Receptors: specialized cells in the sense organs.
Process of sensory receptions:
Receptors receive physical (vision, touch, hearing) or chemical (smell, taste)
stimulation and pass the impulses to the brain in the form of neural impulses.
Most sensory information first goes to the thalamus.
Neurons in the thalamus then send it to the cerebral cortex where impulses are
interpreted by different types of receptors designed to interpret different stimuli.
The brain needs qualitative and quantitative information about a stimulus.
Qualitative: consist of the most basic qualities of a stimulus.
Different sensory receptors respond to qualitatively different stimuli.
Quantitative: consists of the degree, or magnitude, of those qualities.
Coded by the rate of a particular neuron’s firing.
Detection Requires a Certain Amount of the Stimulus
Psychophysics: a subfield developed in the 19th century by Ernst Weber and Gustav Fechner.
It examines our psychological experiences of physical stimuli.
Sensory Thresholds
Absolute Threshold: the minimum intensity of stimulation that must occur before
you experience a sensation.
Difference Threshold: sometimes called a just noticeable difference, is the minimum
amount of change required for a person to detect a difference between two stimuli.
Weber’s Law: just noticeable difference between two stimuli is based on the
proportion of the original stimulus rather than on fixed amount of difference.
Signal Detection Theory
Signal Detection Theory: a theory of perception based on the idea that the detection
of a stimulus requires a judgement – it is not an all-or-nothing-process. Detecting a
stimulus is not an objective process. Instead it is a subjective process with two
components:
Sensitivity to the stimulus in the presence of distractions from other stimuli.
Chapter 5: Sensation and Perception
Synesthesia: the production of a sense impression relating to one’s sense or body part by
stimulation of another sense or body part.
5.1 How Does Perception Emerge from Sensation?
LEARNING OBJECTIVES:
Distinguish between sensation and perception.
Describe how sensory information is translated into meaningful stimuli.
Explain the concept of threshold. Distinguish between absolute threshold and
difference threshold.
Explain how thresholds are related to signal detection and sensory adaption.
Sensation: the detection of external stimuli and the transmission of this information
to the brain.
Perception: the brain’s further processing, organization, and interpretation of
sensory signals/information.
Sensation = detection
Perception = construction
- Stimulus sensation sensory coding perception
Experience guides sensation and perception, but sensation and perception are also
integrated into experience.
Bottom-up Processing: perception based on the physical features of the stimulus.
Top-down Processing: how knowledge, expectations, or past experiences shape the
interpretation of sensory information.
Context affects perception.
What makes proofreading our own work so difficult.
Sensory Information Is Translated into Meaningful Signals
Sensory Coding: the process of sensory systems translating the physical properties of stimuli
into patterns of neural impulses.
, Transduction: the process by which sensory stimuli are converted to signals the brain
can interpret.
Sensory Receptors: specialized cells in the sense organs.
Process of sensory receptions:
Receptors receive physical (vision, touch, hearing) or chemical (smell, taste)
stimulation and pass the impulses to the brain in the form of neural impulses.
Most sensory information first goes to the thalamus.
Neurons in the thalamus then send it to the cerebral cortex where impulses are
interpreted by different types of receptors designed to interpret different stimuli.
The brain needs qualitative and quantitative information about a stimulus.
Qualitative: consist of the most basic qualities of a stimulus.
Different sensory receptors respond to qualitatively different stimuli.
Quantitative: consists of the degree, or magnitude, of those qualities.
Coded by the rate of a particular neuron’s firing.
Detection Requires a Certain Amount of the Stimulus
Psychophysics: a subfield developed in the 19th century by Ernst Weber and Gustav Fechner.
It examines our psychological experiences of physical stimuli.
Sensory Thresholds
Absolute Threshold: the minimum intensity of stimulation that must occur before
you experience a sensation.
Difference Threshold: sometimes called a just noticeable difference, is the minimum
amount of change required for a person to detect a difference between two stimuli.
Weber’s Law: just noticeable difference between two stimuli is based on the
proportion of the original stimulus rather than on fixed amount of difference.
Signal Detection Theory
Signal Detection Theory: a theory of perception based on the idea that the detection
of a stimulus requires a judgement – it is not an all-or-nothing-process. Detecting a
stimulus is not an objective process. Instead it is a subjective process with two
components:
Sensitivity to the stimulus in the presence of distractions from other stimuli.
