SLK 120
CHAPTER 4:
Sensory Systems and Perception
1.
STIMULUS
SENSATION: Physiological process of taking in raw physical energy from stimuli via the sensory
receptors of our different sensory organs.
PERCEPTION: Psychological process, whereby sensory neurologaiacl signals that rewach the brain
are selected, organised & interpreted, so that we can make sense of & attach
meaning to sensations.
WE PERCEIVE STIMULI IN DIFFERENT WAYS, DUE TO 3 FACTORS:
1. Functionality of our individual sensory systems.
2. Different types of stimuli that occur in our environments.
3. Our unique experiences.
THRESHOLDS
THRESHOLD: Point at which a stimulus triggers a response.
STIMULUS INTENSITY: How intense a stimulus has to be for it to be detected.
ABSOLUTE THRESHOLD: Weakest detectabale stimulus, it is not absolute (exact) & a
gradual exposure to stimuli will lower the threshold.
JUST NOTICEABLE DIFFERENCE (JND): A.K.A. Difference threshold – identifies the lowest
intensity of a stimulation needed to create a
noticeable difference between stimuli.
, SIGNAL-DETECTION THEORY
SIGNAL-DETECTION THEORY: Acknowledges the absolute threshold & JND theories, but
emphasises the psychological state that influences the
detection of a stimulus
To predict when the slightest signal of sensation is experienced.
Acknowledges the sensory process of an individual AND the strength of a signal i.t.o.
identifying threshold (stimulus intensity).
Also suggest possible limitations & influences can affect identification of sensation &
signal-detection – influencing concept of threshold.
Suggests an individual can be an active decision-maker in making perceptual judgements
& detecting signals.
Also explains that detection of stimuli can be influenced by variety of factors – such as
personal experiences, biases, expectations, degrees of motivation, previous exposures to
stimuli, personal sensitivity, level of ability alertness, willingness & confidence ti respond,
as well as personal strengths.
Detection of additional stimuli can make sensation signals weaker.
PERCEPTION WITHOUT AWARENESS
SUBLIMINAL PERCEPTION: Psychological perception of OR reaction to a stimulus that
occurs without awareness.
SENSORY ADAPTATION
SENSORY ADAPTATION: Occurs when stimulation sensitivity gradually weakens due
to ectended exposure of a specific stimuli.
, 2.
THE STIMULUS: LIGHT
SATURATION: Perception of colour.
AMPLITUDE OF LIGHT: Brightness.
WAVELENGTH OF LIGHT: Colour.
Stimulus of vision = light
Almost all subjects reflect light, exceptions emit it (such as the sun).
Light travels quickly in form of an electromagnetic radiation wave.
Light waves can be measured by height (amplitude) and length (wavelength) in its
highest point (where amplitude is at its highest point).
Height of wavelength will influence perception of brightness.
Distance between peaks mainly effects ones perception of colour or shade.
Colours are perceived according to the type and visibility of the light waves that reflect
off the surface of an object.
The purer the light wave – the more saturated it will be.
If wavelength consists of only one colour – considered pure, therefore highly saturated.
If light wave contains mixture of colours – purity and saturation of colour will lessen.
CHAPTER 4:
Sensory Systems and Perception
1.
STIMULUS
SENSATION: Physiological process of taking in raw physical energy from stimuli via the sensory
receptors of our different sensory organs.
PERCEPTION: Psychological process, whereby sensory neurologaiacl signals that rewach the brain
are selected, organised & interpreted, so that we can make sense of & attach
meaning to sensations.
WE PERCEIVE STIMULI IN DIFFERENT WAYS, DUE TO 3 FACTORS:
1. Functionality of our individual sensory systems.
2. Different types of stimuli that occur in our environments.
3. Our unique experiences.
THRESHOLDS
THRESHOLD: Point at which a stimulus triggers a response.
STIMULUS INTENSITY: How intense a stimulus has to be for it to be detected.
ABSOLUTE THRESHOLD: Weakest detectabale stimulus, it is not absolute (exact) & a
gradual exposure to stimuli will lower the threshold.
JUST NOTICEABLE DIFFERENCE (JND): A.K.A. Difference threshold – identifies the lowest
intensity of a stimulation needed to create a
noticeable difference between stimuli.
, SIGNAL-DETECTION THEORY
SIGNAL-DETECTION THEORY: Acknowledges the absolute threshold & JND theories, but
emphasises the psychological state that influences the
detection of a stimulus
To predict when the slightest signal of sensation is experienced.
Acknowledges the sensory process of an individual AND the strength of a signal i.t.o.
identifying threshold (stimulus intensity).
Also suggest possible limitations & influences can affect identification of sensation &
signal-detection – influencing concept of threshold.
Suggests an individual can be an active decision-maker in making perceptual judgements
& detecting signals.
Also explains that detection of stimuli can be influenced by variety of factors – such as
personal experiences, biases, expectations, degrees of motivation, previous exposures to
stimuli, personal sensitivity, level of ability alertness, willingness & confidence ti respond,
as well as personal strengths.
Detection of additional stimuli can make sensation signals weaker.
PERCEPTION WITHOUT AWARENESS
SUBLIMINAL PERCEPTION: Psychological perception of OR reaction to a stimulus that
occurs without awareness.
SENSORY ADAPTATION
SENSORY ADAPTATION: Occurs when stimulation sensitivity gradually weakens due
to ectended exposure of a specific stimuli.
, 2.
THE STIMULUS: LIGHT
SATURATION: Perception of colour.
AMPLITUDE OF LIGHT: Brightness.
WAVELENGTH OF LIGHT: Colour.
Stimulus of vision = light
Almost all subjects reflect light, exceptions emit it (such as the sun).
Light travels quickly in form of an electromagnetic radiation wave.
Light waves can be measured by height (amplitude) and length (wavelength) in its
highest point (where amplitude is at its highest point).
Height of wavelength will influence perception of brightness.
Distance between peaks mainly effects ones perception of colour or shade.
Colours are perceived according to the type and visibility of the light waves that reflect
off the surface of an object.
The purer the light wave – the more saturated it will be.
If wavelength consists of only one colour – considered pure, therefore highly saturated.
If light wave contains mixture of colours – purity and saturation of colour will lessen.
