Psyc 313 Day 3

1
Psyc 313 Day 3
2
Early Memory Research

• Ebbinghaus in 1885 conducted some of the first
  experimental studies on memory
• E.g. subject required to learn (successfully
  recite) 420 lists of 16 nonsense syllables each
  (chosen since they were assumed to have no prior
  associations)
• Repetition facilitates memory
• Memory declines as a function of time (forgetting
  curve)
• Found savings reduction in trials needed to
  relearn a list
• Discovered serial position effect (items at
  beginning and end of a a list are more readily
  recalled)
• Assumptions memory is a mechanical, passive
  registration of events set isolates memory from
  other cognitive functions (intention,
  interpretation)

3
Ebbinghaus Forgetting Curve
4
More Early Memory Research

• Bartlett (1932) tried to study memory in a less
  artificial (more realistic) setting, assessing
  subjects memory for folk tales and stories
• Found that many details left out, others inserted
• Memory was a reconstructive process, rather
  than a reproductive process
• Reconstruction is guided by schemata, generalized
  knowledge structures
• Alternative to mechanistic, S-R approach to
  memory couch as a social psychology.

5
Internal vs. Ecological Validity

• An advantage of experiment (as opposed to
  descriptive research and mere observation) is the
  level of control researchers have (manipulation
  of independent variable)
• A disadvantage is that the highly controlled
  setting in a laboratory is unlike the reality of
  everyday life
• Often there is a trade-off between internal and
  ecological validity

6
Chapter 3--Early Perceptual Processing

• I. Basic Perceptual Processes
• A. Vision and Audition
• 1. Perception of Depth and Relative Location
• 2. Perceptual Grouping and Perceiving Form
• B. Somesthesis (touch)
• C. Chemosenses Gustation (taste) and Olfaction
  (smell)
• II. Interactive Effects in Perception
• A. Interactions Between Sensory Systems
• 1. Vision and Audition
• 2. Vision and Touch
• 3. Synesthesia
• B. Interactions with Experience and Context
• Illusory Percepts
• Visual Perception Constructed or Direct?
• C. Subliminal Perception?
• III. Sensory Memory
• A. Visual Sensory Memory (iconic memory)
• B. Auditory Sensory Memory (Echoic Memory)
• C. Perceptual Memory

COGNITION AND INDIVIDUAL DIFFERENCES Non-Visual
Sensory Acuity in the Blind COGNITION AND
CONSCIOUSNESS Gestalt Grouping and Illusory
Percepts COGNITION AND NEUROSCIENCE Blindsight
7
Basic Perceptual Processes

• sensation the physiological processes that
  underlie information intake
• perception the psychological processes involved
  in the organization and interpretation of
  sensations
• bottom-up (data-driven) processing
• refers to a flow of info that proceeds from the
  stimulus, to the neural activity driven by the
  stimulus, to its identification
• top-down (conceptually-driven) processing
• refers to the processes whereby we bring previous
  knowledge to bear in determining what we perceive

8
Psychophysics

• The investigation of the mathematical laws
  describing the process by which physical stimulus
  energy become conscious psychological experience
• There may be general laws that cut across sense
  modalities
• absolute threshold the amount of stimulus energy
  needed to perceive a stimulus 50 of the time
• note the absolute is an statistic! For many
  detection trials are in the nature of the case.
• difference threshold the change in the intensity
  of a stimulus that is detectable 50 of the time
  Subject compare a stimulus to a standard.

Also called the just noticeable difference
(jnd) The jnd turns out to be relative to the
intensity of the standard Webers Law the jnd
is a constant proportion of the intensity the
original stimulus (valid across sensory systems)
9
Signal Detection Theory

• an approach that characterizes perceptual
  experiences as the joint product of sensitivity
  (knowledge that something was perceived) and
  response bias (the degree of willingness to
  report it)
• Some subjects prone to miss stimulus, others to
  false alarms may adopt response strategies.
• Comparing a subjects record of hits and false
  alarms gives a better indication of sensitivity

10
Transduction in Vision

• Three main physical properties
• Wavelength Corresponds to experience of hue
• Intensity Corresponds to experience of
  brightness
• Purity Corresponds to saturation (richness)
• Retina contains light-sensitive cells that react
  to light by creating neural impulses
• Rods Sensitive even in low light (only to shades
  of grey) and movement
• 120 million in retina, concentrated in periphery
• Cones Sensitive to fine detail (visual acuity)
  and colour
• 6 million in retina, concentrated in the fovea
  (100µ)
• Photopigments create chemical reaction to light
• These break down in bright light, regenerate
  after time in low light (this enables dark
  adaptation)

11
Binocular Visual Cues to Depth

• Cues due to physiological processing in the
  visual system
• convergence the degree to which the two eyes
  turn inward toward one another when brought to
  fixation on a common point
• convergence and accommodation provide reasonably
  accurate information about the depth of
  relatively close objects in the environment (10
  feet)
• retinal disparity refers to the differing views
  of the scene offered by each retina fusion of
  these images leads to stereopsis, or 3-D vision
• accommodation the change in the shape of the
  eyeballs lens with changing distance of a target
• Happens in both eyes, but also within each eye.

12
Musculature of Human Eye
http//www.eyedesignbook.com/ch6/fig6-14bBG.jpg
13
What shows depth in this 2D display?
14
Monocular Visual Cues to Depth

• interposition objects that occlude other objects
  are perceived as nearer in space
• relative size if two objects are known to be
  similar in size, yet one is smaller, the smaller
  object is perceived as more distant
• perspective cues those that arise from the
  changes in information received by the eyes as
  our distance from and/or perspective on an object
  changes
• linear perspective two parallel lines converge
  at a distance
• texture gradient the closer we are to some
  object, the more of its texture we see
• aerial perspective objects that are further away
  appear hazy and unclear
• shading shaded objects appear father away than
  non-shaded objects
• motion parallax the apparent motion of near
  objects is more rapid than for far objects

15
Sound Localization

• Depends critically on the fact that we have two
  ears
• inter-aural time differences (ITD)--the
  discrepancy in time of arrival of a sound at each
  ear the greater the discrepancy, the easier it
  is to localize the sound on the side where the
  sound first arrived
• important for localization of low-frequency
  sounds
• inter-aural intensity differences (IID)--the
  difference in a sound's intensity as it enters
  each ear greater intensity in one ear indicates
  that the sound is closer to that ear
• important for localization of high-frequency
  sounds
• ITD and IID specify a range of possibilities
  about where the sound is coming from, but don't
  uniquely specify an exact location

16
Gestalt Principles Illustrated
Source http//www.cl.cam.ac.uk/Teaching/2000/AGra
phHCI/HCI/hcinotes.html
17
Gestalt Principles of Grouping types

• figure-ground the tendency to segregate visual
  scenes into a background and a figure that
  appears to be superimposed against it
• regions designated as figure tend to be smaller
  and have more symmetrical features
• elements in the lower region of the visual field
  are more likely to be seen as figure
• proximity objects that are near one another tend
  to be grouped together
• similarity items that are similar to one another
  tend to be grouped together
• good continuation the tendency to perceive lines
  as flowing naturally, in a single direction
• closure the tendency to connect contours that
  are almost, but not quite connected
• common-fate the tendency to group elements
  together if they are moving in the same
  direction, or at the same speed
• uniform connectedness elements that are
  connected in some way will be grouped together
• common region elements that seem to belong to a
  common designated area, or region, will be
  grouped together
• Note grouping principles are also employed in
  the perception of auditory scenes (e.g., music)
  rhythm words melodies
• E.g. Marzi doats n doze edoats n lidul lamzey
  divey

18
Ambiguous Gestalts
19
Gestalt and Global Precedence

• apprehending wholes or configurations is a
  primitive (natural tendency of our perceptual
  system) and is done fairly easily and
  automatically
• Navon (1977) participants viewed letters that
  were composed of other letters or objects (e.g.,
  an H made of Ss)
• conditions
• global-directed condition identify the global
  letter
• local-directed condition identify the local
  letters/objects
• stimuli
• the big letters were of three types
• the global and local features were consistent (a
  big H made of little H's)
• the global and local features conflicted (a big H
  made of little S's)
• the global and local features were neutral with
  respect to one another (a big H made from little
  rectangles)
• prediction
• if global processing takes precedence over local
  processing
• conflicting letters should only pose a problem in
  the local-directed condition, because in this
  condition, one can't help but see the big letter
• if this letter conflicts with the one
  participants have to identify, responses will be
  slower and more prone to error

20
Gestalt and Global Precedence

• results
• responses to the big letters (global-directed
  condition) were much faster than to the small
  ones (local-directed condition)
• demonstrates that perceptually it is easier to
  perceive the whole than its parts
• interference from the conflicting letter had
  markedly different effects on global-directed and
  local-directed trials
• global-directed condition didn't matter whether
  the local letters were consistent, conflicting,
  or neutral,
• the local-directed condition whether the global
  letter was consistent or conflicting made a huge
  difference if it conflicted, participants RT was
  slowed
• even when instructed to look for the local
  letters, participants couldn't help but encode
  the global one
• implication
• global features of a scene are registered first,
  followed by a systematic analysis of the local
  features
• perception of the "whole" of a scene is a feature
  of the visual environment that is registered
  automatically, without the need for higher-level
  interpretation or analysis (global precedence
  effect)

21
What letter is it?
22
Somesthesis (Touch)

• basic dimensions roughness/smoothness
  hardness/softness sponginess
• passive touch/active touch distinction
• passive touch does not involve exploration
• used to gather basic information impinging on our
  skin senses (tactile acuity)
• factors affecting tactile acuity
• varies with body area
• decreases with age
• active touch (haptics)
• involves the addition of information from the
  kinesthetic sense (information about body
  position and movement--usually the hand) to the
  information gathered from passive touch

23
Haptic Exploration

• Klatzky, Lederman, and Metzger (1985)
• asked participants to identify 100 common
  objects, using nothing but their hands
• identified each object in a matter of 1 to 2
  seconds, with virtually no errant identifications
• based on observations authors identified six
  exploratory procedures
• static contact ascertains the temperature of an
  object
• unsupported lifting helps ascertain information
  about weight
• lateral motion is used to extract information
  about texture
• pressure is used to extract information about
  hardness
• contour following provides information about
  shape
• enclosure provides information about object size
• haptic exploration proceeded in an orderly manner
• first EPs performed were enclosure and
  unsupported lifting in order to determine it's
  basic shape and weight
• the rest of the EPs were used in further
  exploration to determine size, shape, and function

24
Haptic Exploration

• Exploration proceeds in orderly fashion, usu.
  starting with enclose and lifting.
• Lateral motion gives texture
• Pressure shows hardness
• Static contact gives temperature
• Lifting affords weight
• Enclosure gives size
• Contour affords shape

25
Pavani, Spence, Driver (200)
26
Chemosense Gustation

• 1. Gustation (taste)
• basic dimensions salty, sweet, bitter, sour,
  (some add savory)
• flavor the combination of the four basic tastes,
  along with factors such as smell, texture, and
  temperature
• major issues
• how many tastes are there?
• when we taste something complex is each taste
  dimension discernible?
• some say yes because there are taste receptors
  that are maximally sensitive to each of the four
  basic tastes
• others say no, adopting a Gestalt approach to the
  taste experience--component tastes fuse to
  produce a singular perception that can't be
  described in terms of basic elements
• sense of taste is closely linked to sense of
  smell

27
Chemosense Olfaction

• 2. Olfaction (smell)
• people vary in sensitivity to smells and ability
  to discriminate among smells so it has been
  difficult to determine if there a set of primary
  smells
• olfactory-verbal gap our difficulty describing
  odors difficulty identifying an odor correctly
• as few as 50 of presented odors are labeled
  correctly identification accuracy increases when
  tested with a choice of labels
• women are better at labeling smells than men
• tip-of-the-nose phenomenon
• inability to come up with the verbal label for an
  odor in spite of a strong feeling that one knows
  what the odor is

28
Interactive Effects in Perception Vision and
Audition

• Saldana and Rosenblum (1993)
• Experimental Condition presented participants
  visually with a cello being plucked (or bowed) in
  conjunction with the opposing auditory stimulus
  (a cello being bowed or plucked)
• Control Condition presented with only the
  auditory stimulus
• compared to those in the control condition,
  participants in the experimental condition tended
  to "hear" what they saw rather than what was
  presented in the auditory mode
• McGurk and MacDonald (1976)
• participants were presented with speech sounds
  (e.g., /bc/) simultaneously, they were presented
  with a (silent) visual display of a speaker
  pronouncing a different speech sound (e.g., /gc/)
• an "average" of the two speech sounds (/dc/) is
  the resulting perception (McGurk effect)
• Calvert et al. (1997)
• performed functional magnetic resonance imaging
  (fMRI) on individuals who were watching a
  speaker's lips in the absence of any auditory
  stimulation
• simply watching these speech-related lip
  movements led to the activation of the auditory
  cortex, located in the temporal lobe of the brain
• this activation didn't occur for just any type of
  facial movement the auditory cortex was only
  activated when facial movements were linguistic
  in nature

29
Interactive Effects in Perception Vision and
Touch

• Pavani, Spence, and Driver (2000)
  experiment 1
• participants wore rubber gloves and their hands
  were placed out of sight
• a small sponge cube was held with the thumb and
  forefinger of each hand these cubes were
  equipped with tiny vibrators that could either
  vibrate the thumb or forefinger position
• above the hand-held sponge cubes were two visible
  sponge cubes these sponge cubes were equipped
  with an LED at the top and bottom, which would
  light up simultaneously when the hand-held cube
  was vibrated
• the relationship between which LED was activated
  (top or bottom) and which position received the
  vibration (forefinger/top or thumb/bottom) was
  random but lights and vibration always occurred
  at the same time
• participants were to identify the source of the
  vibration reaction time for this judgment was
  recorded
• on half of the trials, rubber hands were placed
  on the visible cubes (the ones with the
  LED's)--the participant's hands were in identical
  rubber gloves, and the fake rubber hands were
  positioned so that they looked like they could
  have been the participants' hands

30
Interactive Effects in Perception Vision and
Touch

• results
• RT to identify the source of the vibration was
  slower when the light mismatched the vibration
  position than when it matched
• the dummy hands significantly accentuated this
  interfering effect--seeing the light at a given
  position on the dummy hand gave rise to an
  illusory sensation of feeling that vibration in
  the corresponding position below
• Pavani, Spence, and Driver (2000)
  experiment 2
• replicated the procedure, but with misaligned
  rubber hands that were clearly fake
• the misaligned hands had no effect on RT
• the dummy hands in experiment 1 must have
  resulted from participants experiencing the dummy
  hands (to some extent) as their own

31
Synesthesia

• strong synesthesia
• experiences in which input from one sensory
  system produces an experience not only in that
  modality, but in another as well
• very rare (less than 1 out of every 2000
  individuals)
• female synesthetes outnumber males about six to
  one may have a genetic basis
• weak synesthesia
• stimuli from one sensory modality are associated
  with another
• higher-pitched tones are placed with lighter
  colors
• high pitched tones are more quickly classified
  when presented along with white squares than when
  presented with black squares the opposite
  pattern holds for low-pitched tones (congruence
  effect)

32
Synesthesia

• what leads to synesthetic correspondences, and do
  similar mechanisms underlie the strong and weak
  varieties?
• lower-level explanations
• information from one sensory modality is
  mis-coded and/or mis-processed by another
  modality
• strong synesthesia--could be due to some
  abnormality in the development of neural
  connections
• weak synesthesia--similar neural processes
  transduce associated stimuli (e.g., low tones and
  dark colors), leading the two to be associated
• higher-level explanations
• synesthetic effects derive from the way we think
  about and linguistically code our sensory
  experiences
• through experience we build up an abstract
  network of concepts that applies to these
  experiences
• some of these concepts become strongly associated
  (e.g., light and high-pitched, dark and
  low-pitched) such that one can automatically
  activate the other

33
Perceptual Memory

• a more stable and (relatively) long-lasting
  representation of information that retains the
  perceptual characteristics of a stimulus
• an auditory perceptual memory might range
  anywhere from replaying the last thing said by a
  friend in conversation a few seconds ago (a
  short-term memory), to replaying your favorite
  song from the Broadway show you saw last month (a
  long-term memory)
• a visual perceptual memory could take the form of
  visually running through the last few places
  youve looked for your lost keys (a short-term
  memory), to recalling the horrible sight of the
  9/11 attacks on the World Trade Center (a
  long-term memory)
• similarities and differences between perceptual
  memory and sensory memory
• both retain modality-specific characteristics
  present when the event was encoded
• sensory memory is an extremely fragile and
  transient replica thats present for just a
  fraction of a second
• perceptual memories can last for seconds, days,
  even years

34
(No Transcript)
35
(No Transcript)
36
(No Transcript)
37
(No Transcript)
38
(No Transcript)
39
(No Transcript)
40
(No Transcript)
41
(No Transcript)
42
(No Transcript)
43
(No Transcript)
44
(No Transcript)