3. Top-down Processing

Question 1

constructivism and context

Answer 1

• contextual cues allow us to decode stimulus
• can facilitate or hinder processing (appropriate vs inappropriate)

Question 2

illusions as experience

Answer 2

• gestalt principles were believed to be responsible for the illusion
• we look for regularities in the env.

Question 3

cross-cultural experience

Answer 3

refer to slide 7 of powerpoint

Question 4

constructivism and world recognition

Answer 4

• one of the most researched areas in experimental psychology is language
• most early studies focused on elementary features in perception (identification and recognition) and memory (serial recall)
  1. frequency effects
  2. similarity effects
  3. semantic contexts effects

Question 5

constructivism and world recognition: frequency effects

Answer 5

high freq words produce better ACC and fast RT than low freq words

Question 6

constructivism and world recognition: similarity effects

Answer 6

• words exist in context of other words
• words with many neighbours (book, look, took) produce poorer results than those with fewer neighbours
• issues of distinctiveness/competition (recall uncertainty in info)

Question 7

constructivism and world recognition: semantic context effects

Answer 7

• performance increases for word recognition if a word is presented with semantically similar words (e.g pen paper ink) or in a sentence
• allows deeper meaning of the word

Question 8

word superiority effect

Answer 8

• when people are more accurate in identifying a letter when it is part of the word
• RECALL discussion of info theory and decrease of uncertainty
• more likely to recall/detect stimulation when presented in context of words due to LTM
• refer to slide 11-12 for example

Question 9

interactions between bottom up and top down mechanisms

Answer 9

• studies suggest that there is an interaction between bottom up and top-down mechanisms which process info in parallel
• the IAM (interactive activation model) is a pandemonium-like system that includes both BU and TD processing

Question 10

the IAM

Answer 10

the study:
1. features, letters and words were built from the alphabet (slide 14)
2. the system was equipped with 1179 letter words
the IAM elements
1. perceptual processing occurs within a system in which there are multiple levels of processing
- each level is concerned with forming a representation of the input at a different level of abstraction (features, letters, words)
- they use output of one system as their input
2. visual perception involves parallel processing
3. visual processing occurs at several levels at the same time

Question 11

the IAM: representational assumptions

Answer 11

1. there is a node for each word and each letter (in each letter position)
2. the nodes are organized into levels
3. the nodes are connected to all other nodes within levels or between adjacent levels
4. connections may be excitatory or inhibitory
   refer to slide 20 of powerpoint

Question 12

the IAM: operational assumptions

Answer 12

1. when stimulus is represneted, a set of featural inputs = made
2. initially, all nodes are in a quiescent state
3. features activate the letter s, which in turn activate the words, which finally send back activation to the letters
4. the answer of the system is the letter with the most activation at a given time
   refer to slides 22-23 of powerpoint

Question 13

the IAM: conclusions

Answer 13

• with a limited nb of clearly defined postulates, the IAM can account for the word superiority effect
• this model is a direct precursor of contemporary connectionist models

Question 14

speech perception as categorical perception

Answer 14

• speech perception examines how we identify speciial kinds of auditory stimuli
• speech perception examines how we identify special kinds of auditory stimuli
• in most types of perception people perceive stimli along a continuum - does this hold for speech stimulus
• speech errors (and typos) seem to indicate a nb of interesting aspects of our language

Question 15

speech perception: bottom-up and top-down

Answer 15

when listening to a speaker, we are required to perform numerous operations

Question 16

speech perception: phonemes

Answer 16

• auditory cues are used to differentiate speech sounds
• phonemes: represent smallest unit of sound that provides meaningful info in terms of the meaning of the word
  1. stop consonants: b/d/g
  2. voicing (unvoiced or voiced): p/b
• voice-onset-time: delay between
  1. release of articulators
  2. vibration of the vocal folds

Question 17

auditory vs speech perception

Answer 17

• when presented with stimuli, we would expect that the proportion of ‘loud’ responses would increase with actual increase in loudness
• looks like psychophysics
• allows to detect different stimuli (slide 28)
• people have access to acoustic properties of the stimuli, then group them into phonemes they have stored in LTM

Question 18

What should we expect to see in speech sounds auditory stimuli?

Answer 18

• a systematic decrease in the nb of responses reported as a given phoneme
• despite differences, neighbouring stimuli within a category are perceived as the same
• we observe a discontinuity or category boundary

Question 19

speech perception: crosscultural findings

Answer 19

• categorical perception is a orbust phenomena, however, we must recognize that it is a function of individual experience
• there is some element of learning regarding different category boundaries
• certain lab techniques can be used to add a category boundary (e.g. non-native phonemic category can be perceived)
• prior linguistic knowledge can impair phonemes sometimes (being overridden by our knowledge)

Question 20

what is the trigger to an affective response?

Answer 20

• initially encoding a stimlus, which starts a cascade of processing that leads to an affective response
• refer to diagram in notebook page 20

Question 21

multimodal perception

Answer 21

• most perception in our everyday lives is multimodal wherein we integrate different types of info
• McGurk effect
• multimodal and multidimensional cues also provide the basis for illusions (e.g. vestibular and visual = crazy kitch)

Question 22

multimodal perception: McGurk effect

Answer 22

• observed when we integrate info from visual and auditory (e.g. b vs g) modalities
• results in a perceived qualitative difference (e.g. d)