HPS203 Lecture Notes - Lecture 11: Demand Characteristics, Mental Rotation, Image Scanner
HPS203 Week 11
VISUAL KNOWLEDGE
1. Describe the technique that Galton used to study mental images and the main problem
with this technique
• Introspection; the process through which you ‘look within’ to observe & record the
contents of your own mental life
• Problem with self-report data: perhaps all participants had the same imagery skill, but
some were cautious in how they chose to describe their imagery. Galton’s data might reveal
differences in how people talk about their imagery rather than differences in imagery per
se.
2. Explain what chronometric studies of visual imagery measure
• Chronometric= ‘time measuring’
• To gain more objective data, experiments ask participants to do
something with their images- usually, make a judgement based on the image. We can then
examine how fast people are in making these judgements & with appropriate comparisons
we can use measurements as a basis for testing hypotheses about imagery.
• Help determine what information are prominent in a mental image. Used as a basis for
asking how ‘picture-like’ mental images are.
• Pattern of information included & what information is prominent depends on the mode of
presentation
• Writing a paragraph about a cat: mention distinctive features e.g. claws, whiskers.
Wouldn’t include that cats have heads as this is obvious.
• = Description= prominent features are those that are distinctive and strongly associated
with object being described
• Draw a sketch of a cat: head would be prominent. Whiskers and claws less salient.
• = Depiction= size and position determine what’s prominent
3. Describe Kosslyn’s (1976) results and explain what they tell us about visual imagery
• Group 1: Participants were asked to form a mental image of e.g. a cat & answered yes/no
questions e.g. does the cat have a head, does the cat have claws
• Responses to the head question were faster than the claws
• Suggests that information quickly available in the mental
imagery follows the rules for pictures not paragraphs (depiction)
• Group 2: Participants asked to merely think about cats (with NO MENTION OF IMAGERY)
• When asked does the cat have a head, does the cat have claws (same questions) =
responses to claws were quicker than head (reverse pattern of group 1)
Point being:
• Seems that people have the option of thinking about cats with and without imagery
• When the mode of representation changes (imagery or not), the pattern of information
available changes (rules for paragraph; description or rules for sketch; depiction)
4. Describe Kosslyn, Ball, & Reiser’s (1978) experiment using image- scanning and explain
what the results tell us about visual imagery
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• Participants memorized the landmarks on a map & drew a replica to confirm
memorization.
• Then, participants formed a mental image of the map and imagine a spec moving from
one landmark to another (pressing a button to stop the clock when reached). This gave
researchers scanning times
• Results suggest that participants scan across their images at a constant rate, so that
doubling the scanning distance doubles the time required for the scan.
• There is a clear relationship between travel time & travel distance in mental images that
resembles out in the real world pictures.
• Mental images depict the scene rather than describe it.
5. Describe Shepard’s mental rotation task and explain what the results tell us about
visual imagery
• Participants asked whether displays showed two different shapes or just one shape
viewed from two different perspectives
• Mental rotation task: participants made judgments by imagining one of the forms rotating
until the position matches that of the other form.
• Response times indicated how far apart the two forms were from their initial orientation
• Thus, imagined movement represents actual movement. The greater the degree of
rotation required, the longer the response time takes.
6. Explain why we can discount the demand character of the experiments as a plausible
explanation for the results
• Demand character of the experiment: cues that might signal how they are ‘supposed to’
behave in that situation
• E.g. “the experimenter asked me to scan a long way, and I’d like to make it look like I’m
obey so I’ll wait a moment before hitting
the response button”
• Also- longer scan or greater rotation requires more time, not
because there is some travel time, but because people know that these manipulations
should take more time and do their best to stimulate the process
• Discounted. Images do represent spatial layout.
• Because: experiments have asked participants to make
judgments about spatial layout but have never told participants imagery was relevant to the
task. This should diminish demand characteristics & avoid any suggestion participants
should stimulate some sort of ‘mental travel’
7. Describe the relationship between imaging and perceiving and explain the evidence for
this relationship using Segal and Fusella’s experiments
• Segal & Fusella study: participants asked to detect faint signals (dim visual stimuli/soft
tones) in one of two conditions; while forming a visual image before their ‘minds eye’ or
while forming an auditory image before their ‘mind’s ear’ (thus, 2 types of signals & 2 types
of imagery).
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
We can then examine how fast people are in making these judgements & with appropriate comparisons we can use measurements as a basis for testing hypotheses about imagery: help determine what information are prominent in a mental image. Used as a basis for asking how picture-like" mental images are: pattern of information included & what information is prominent depends on the mode of presentation, writing a paragraph about a cat: mention distinctive features e. g. claws, whiskers. Wouldn"t include that cats have heads as this is obvious: = description= prominent features are those that are distinctive and strongly associated with object being described, draw a sketch of a cat: head would be prominent. Images do represent spatial layout: because: experiments have asked participants to make judgments about spatial layout but have never told participants imagery was relevant to the task. Poor detection of a visual signal when simultaneously maintaining a visual image.
