PSYCH 7A Lecture Notes - Lecture 7: Retina, Visual Cortex, Lisa Lopes
29 Jun 2018
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PSYCH 7A - Lecture 7 - Sensation & Perception
Sensation vs. Perception
• Sensation
– Process by which physical energy from the environment is detected by the
sense receptors and then encoded as neural signals
• Perception
– Process by which we organize and interpret the sensory information, allowing
us to give meaning to objects and events.
Psychophysics – the study of relationships between the physical characteristics of stimuli and
our psychological experience of them
Absolute Threshold - the minimum stimulation required to detect a particular stimulus 50% of
the time
Difference Threshold
●Difference threshold (aka just noticeable difference) – the minimum difference a person
can detect between any two stimuli 50% of the time.
●Weber’s Law – to be perceived as different, two stimuli must differ by a constant
proportion of that stimulus (depending on the type of stimulus!).
●Proportion depends on type of stimulus:
○Weights – must differ by about 2%
○Sound Intensity – must differ by about 4%
○Frequency – must differ by about 0.3%
Senses
●Transduction – converting one form of energy to another
●With regards to sensation, transduction means converting stimulus energies (sights,
sounds, etc), into neural impulses that our brain can interpret
Vision: Light Energy
●Hue (color)
○ determined by wavelength - the distance from one wave peak to the next
○ visible light between 400-700 nm
●Intensity
○determined by wave’s amplitude
○determines brightness of colors
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Document Summary
Psych 7a - lecture 7 - sensation & perception. Process by which physical energy from the environment is detected by the sense receptors and then encoded as neural signals: perception. Process by which we organize and interpret the sensory information, allowing us to give meaning to objects and events. Psychophysics the study of relationships between the physical characteristics of stimuli and our psychological experience of them. Absolute threshold - the minimum stimulation required to detect a particular stimulus 50% of the time. Difference threshold (aka just noticeable difference) the minimum difference a person can detect between any two stimuli 50% of the time. Weber"s law to be perceived as different, two stimuli must differ by a constant proportion of that stimulus (depending on the type of stimulus! Weights must differ by about 2% Sound intensity must differ by about 4% Frequency must differ by about 0. 3% Transduction converting one form of energy to another.
