Lecture 2

Cards (24)

  • Categories are useful
    • help organize information into meaningful groups
    • = facilitate cognitive processes - perception, memory, decision-making
    • grouping similar items = efficiently process & understand complex information, make predictions, communicate effectively
  • Exemplar theory 

    • when encounter new stimulus = compare to all specific examples or instances of category we have previously encountered
    • emphasizes importance of storing & remembering individual instances of a category
  • Prototype theory 

    • when encounter a new stimulus = mentally compare it to abstract representation or "prototype" we have stored for category
    • prototype based on an average of all instances of category we have encountered in past
    • emphasizes role of generalized representations
    • = simplified & efficient way of categorizing new stimuli
  • Category learning in pigeons (Herrnstein, Loveland, & Cable, 1976)
    • thousands of pictures used in training
    • successful discrimination of novel pictures at test
    • learned categories of water & people - even specific person
    • also tropical fish
  • Styles of paintings - Watanabe, Sakamoto, Wakita 1995
    • pigeons' ability to discriminate paintings
    • = able to distinguish between artists' works = demonstrating level of visual discrimination previously thought to be exclusive to humans
  • Discrimination among multiple categories
    (Bhatt, Wasserman, Reynolds, & Knauss, 1988)
    • 4 categories learned
    • Novel pictures classified successfully
    • Performance maintained when training pictures never repeated
  • Larger sets make for better categories (Bhatt, 1988)
    larger sets = poorer learning for training items but better performance on test items
  • Categorisation is capuchins is successful, but…
    (D’Amato & van Sant, 1988)
    • Successful discrimination of people from non-people
    some errors were unusual
    • Photographs classified as people when looked nothing like people
    • In training set, only people slides contained red
    • Non-people test slides containing red misclassified
  • Categorisation determined by features (Huber & Lenz 1993)
    • 4 stimulus dimensions used = each dimension = 3 possible values
    • Pigeons trained to peck at faces with sum greater than 0 - behavior reinforced
    • rate of pecking response determined by sum of features in stimuli
    • aimed to assess how pigeons categorized & responded to stimuli based on sum of features
  • Aust & Huber 2006
    • Perhaps non-human animals don’t know what pictures stand for - just respond based on low-level features, but…
    • pigeons trained to recognize pictures of objects through visual categorization task
    • = suggest pigeons possess representational insight = able to generalize learning to novel stimuli
    • highlights cognitive abilities of pigeons in visual recognition tasks - perceptual & categorization capabilities.
  • Aust & Huber 2010 - experience
    • investigates pigeons' recognition of human body parts in pictures
    • trained to discriminate handless or headless humans & nonhumans
    • Some had prior exposure to real human heads - others didn't
    • without prior experience of heads failed to show preference to pictures of missing parts over arbiturary skin patches
    • Suggests evidence of representational insight in pigeons
    • Highlights influence of real-world experience on visual categorization tasks
  • Concrete categories
    • groups of objects defined by physical attributes, properties, characteristics that can be directly perceived through senses
    • all pictures of people have common concrete attributes
    • are identifiable physical features present
    • simple associative learning can explain acquisition of concrete categories
  • Abstract categories
    • groups of concepts defined by shared characteristics or properties not directly observable through senses
    • based on subjective interpretation
    • 'son' - based on relationship
    • evidence that non-humans can learn relational categories = mixed
  • categorising perceptual features
    • human infants tend to categorize objects based on perceptual features rather than abstract categories = more conceptual in nature
    • evidence suggests non-human animals also rely on perceptual features for categorization
    • perhaps non-human animal struggle to learn realtional categories?
  • Same/ different learning in pigeons
    • rewarded for pecking at flanker matching sample image
    • group 2 - 2 sample pictures - fast learning
    • only 4 combinations for g2 = may have remembered correct response for each configuration
    • novel pictures = no evidence of same/ different rule
    • group 152-samples = 18 months to learn - generalised to novel pictures
  • Matching to sample
    • Pigeons find task very difficult
    • other species able to master more easily
  • Irene Pepperberg's parrot Alex
    easily respond verbally to questions about what was same/ different
  • Why do pigeons find same/ different judgments so difficult?
    • pigeons can perceive sameness, but it lacks salience? - doesn't stand out?
    • Pigeons might prefer to use individual stimuli - rather than make abstract judgments
    • Training with lots of instances should help
  • Effects of varying length of training
    • size of training set strongly influenced transfer to novel items - more training higher transfer correct
    • same effect seen of rhesus monkeys & capuchins - but performance generally better
  • Abstract rules - opposites
    • abstract rules - dictate how make decisions
    • how fill in gaps of pattern - responses to new based on similarity or opposites rule
    • Humans: rule-based - decisions cos of abstract rules or principles
    • Rats & pigeons: similarity-based - of stimuli
    • Humans under cognitive load: similarity-based
  • Second-order relationships in chimpanzees 

    • young chimpanzees, matching problem - pairs of objects attached to a board - select pair of objects whose relationship matched relationship of sample
    • Despite extensive training - over 1000 trials = chimpanzees failed to demonstrate ability to perceive second-order relationships.
    • Children under 5 also struggle with similar tasks -suggests complexity of problem
  • Testing second-order relationships in chimpanzees - Further research
    indicated chimpanzees could distinguish between relationships when presented with different pairs of objects after playing with one pair
  • What does it mean?
    • lots of evidence that non-humans animals can form categories based on physical features
    • can be stored using concrete code
    • moderate amount of evidence of learning about relationships - mostly from matching experiments
  • sameness might have a concrete component 

    • may not be entirely abstract or purely conceptual
    • idea of similarity might be influenced by concrete elements or characteristics.