PPERCEPTION LECTURE 1
• Familiarity effect – empirical findings that reveal how familiarity influences our perceptions of the world
• Recency effect – in perception research, experimental findings that reveal how the recency with which a stimulus has been
encountered influences the perception of the stimulus. In memory research, how items at the end of the list are recalled more
easily
• Expectancy effects – empirical findings that reveal how expectancy can influence our perceptions of the world
• Fodor (1983) – gave a schematic representation of the brain clearly showing how the five senses is are decomposed into its
own subset of input module. Following the sensory encoding, the input modules act as the interface between the world and
the mind of the observer
• Proximal stimulus is the stimulation of the sense organs, while the distal stimulation is the actual physical thing that gave rise
to proximal stimulus. So the brown leather chair is the distal stimulus and the corresponding pattern of the light that imposes
on the retinae is the proximal stimulus
Output is
Information is Distal stimulus is
Stimulus energy Epithelium (surface generated and sent
feeded to the input tried to be
(proximal stimulus) of the body) to the central
modules identified
processors
• Perception – operation of the input modules (perceptual mechanisms)
• Cognition – operation of the central processors (cognitive processes)
• Input modules are informationally encapsulated – once a module receives input, it produces a corresponding output that is
largely insensitive to what the perceiver presumes; regardless of what the consumer would like to hear or see, the input
modules operate according to certain principles that are insensitive to these higher-order considerations
• The job of the input module is to produce the best first guess as to what sort of object may have given rise to this pattern of
input
• The job of the central processors is to assign meaning to this input and make sense of the sense data
• Difference between perception and sensation – sensation is the process of transforming physical stimuli into electrical signals
and perception is the process interpreting these signals for conscious awareness and action
• Perception is generally defined as the process of acquiring knowledge about environmental objects or events via the senses
• Aristotle (384-322 BC): animals must have perception if the are to live
• Perception has evolved to aid the survival and reproduction of organisms
• All of our senses help us to seek out desirable objects and situations and avoid dangerous ones
• 5 senses – somatosensory perception (touch), visual perception (see), gustatory perception (taste), auditory perception (hear),
and olfactory perception (smell)
• The other senses include - Proprioception (sense of body position & movement), Nociception (pain), Thermoception
(temperature)
• Caribour and reindeer can sense light into UV spectrum enabling them to detect camouflaged preys
• Elephants can detect very low frequency sounds enabling them to communicate over large distances
• Snakes can detect infrared radiation enabling them to create a thermal image of their prey
• Senses would not evolve if they did not provide reasonably accurate information about the world, however, this cannot mean
that perception is a necessarily a clear window onto the reality
• For example, the camera and the eye have a similar working, however, the eye cannot transmit the images like a camera and it
has to be interpreted by the brain
, • Illusions – situations where perception differs from reality
• The lilac chaser – there are 11 pink blobs and a blank space arranges in a circle with a cross in between; if the eyes are focused
on the cross then throughout the movie we can see 11 pink blobs and 1 green blobs; this is known as the negative afterimage;
negative afterimages are caused when the eye's photoreceptors, primarily known as rods and cones, adapt to overstimulation
and lose sensitivity. ... The photoreceptors that are constantly exposed to the same stimulus will eventually exhaust their
supply of photopigment, resulting in a decrease in signal to the brain.
• The Hermann grid illusion - The classical explanation of the physiological mechanism behind the Hermann grid illusion is due to
Baumgartner (1960). Baumgartner believed that the effect is due to inhibitory processes in the retinal ganglion cells, the
neurons that transmit signals from the eye to the brain. To each cell there corresponds a small region of the retina called the
receptive field, where photoreceptive rods and cones can trigger an electrical response in that cell. The receptive fields of
adjacent ganglion cells may overlap.
• Some more illusions:
• Ambiguous figures – they are figures that gives rise to two or more distinct perceptions; our perception is rarely ambiguous but
tends to alternate over time; these kinds of images are also known as bistable images
• Example for ambiguous figures are young/old lady, Rubin’s vase; Jastow’s duck/rabbit
• Ambiguous figures sometimes produce different perceptions between different people that are stable over time
• Ambiguous sounds can also give rise to bistable and stable perceptions
• Familiarity effect – empirical findings that reveal how familiarity influences our perceptions of the world
• Recency effect – in perception research, experimental findings that reveal how the recency with which a stimulus has been
encountered influences the perception of the stimulus. In memory research, how items at the end of the list are recalled more
easily
• Expectancy effects – empirical findings that reveal how expectancy can influence our perceptions of the world
• Fodor (1983) – gave a schematic representation of the brain clearly showing how the five senses is are decomposed into its
own subset of input module. Following the sensory encoding, the input modules act as the interface between the world and
the mind of the observer
• Proximal stimulus is the stimulation of the sense organs, while the distal stimulation is the actual physical thing that gave rise
to proximal stimulus. So the brown leather chair is the distal stimulus and the corresponding pattern of the light that imposes
on the retinae is the proximal stimulus
Output is
Information is Distal stimulus is
Stimulus energy Epithelium (surface generated and sent
feeded to the input tried to be
(proximal stimulus) of the body) to the central
modules identified
processors
• Perception – operation of the input modules (perceptual mechanisms)
• Cognition – operation of the central processors (cognitive processes)
• Input modules are informationally encapsulated – once a module receives input, it produces a corresponding output that is
largely insensitive to what the perceiver presumes; regardless of what the consumer would like to hear or see, the input
modules operate according to certain principles that are insensitive to these higher-order considerations
• The job of the input module is to produce the best first guess as to what sort of object may have given rise to this pattern of
input
• The job of the central processors is to assign meaning to this input and make sense of the sense data
• Difference between perception and sensation – sensation is the process of transforming physical stimuli into electrical signals
and perception is the process interpreting these signals for conscious awareness and action
• Perception is generally defined as the process of acquiring knowledge about environmental objects or events via the senses
• Aristotle (384-322 BC): animals must have perception if the are to live
• Perception has evolved to aid the survival and reproduction of organisms
• All of our senses help us to seek out desirable objects and situations and avoid dangerous ones
• 5 senses – somatosensory perception (touch), visual perception (see), gustatory perception (taste), auditory perception (hear),
and olfactory perception (smell)
• The other senses include - Proprioception (sense of body position & movement), Nociception (pain), Thermoception
(temperature)
• Caribour and reindeer can sense light into UV spectrum enabling them to detect camouflaged preys
• Elephants can detect very low frequency sounds enabling them to communicate over large distances
• Snakes can detect infrared radiation enabling them to create a thermal image of their prey
• Senses would not evolve if they did not provide reasonably accurate information about the world, however, this cannot mean
that perception is a necessarily a clear window onto the reality
• For example, the camera and the eye have a similar working, however, the eye cannot transmit the images like a camera and it
has to be interpreted by the brain
, • Illusions – situations where perception differs from reality
• The lilac chaser – there are 11 pink blobs and a blank space arranges in a circle with a cross in between; if the eyes are focused
on the cross then throughout the movie we can see 11 pink blobs and 1 green blobs; this is known as the negative afterimage;
negative afterimages are caused when the eye's photoreceptors, primarily known as rods and cones, adapt to overstimulation
and lose sensitivity. ... The photoreceptors that are constantly exposed to the same stimulus will eventually exhaust their
supply of photopigment, resulting in a decrease in signal to the brain.
• The Hermann grid illusion - The classical explanation of the physiological mechanism behind the Hermann grid illusion is due to
Baumgartner (1960). Baumgartner believed that the effect is due to inhibitory processes in the retinal ganglion cells, the
neurons that transmit signals from the eye to the brain. To each cell there corresponds a small region of the retina called the
receptive field, where photoreceptive rods and cones can trigger an electrical response in that cell. The receptive fields of
adjacent ganglion cells may overlap.
• Some more illusions:
• Ambiguous figures – they are figures that gives rise to two or more distinct perceptions; our perception is rarely ambiguous but
tends to alternate over time; these kinds of images are also known as bistable images
• Example for ambiguous figures are young/old lady, Rubin’s vase; Jastow’s duck/rabbit
• Ambiguous figures sometimes produce different perceptions between different people that are stable over time
• Ambiguous sounds can also give rise to bistable and stable perceptions
