SENSATION & PERCEPTION
Review an experimental study
on sensation and perception
Apply our knowledge of research
to critically exam the study
Develop our own hypotheses for
future research
• Sensation: When energy is detected by
receptors on our sensory organs and
transformed into neural energy (Transduction)
• Perception: The process of organizing
and interpreting sensory
information so that it
makes sense
Occurs in the brain
&
is influenced by our
Perceptual Sets (Experience & Expectations)
as well as by
Context, Emotions, & Motivation
Signal Detection Theory
• Signal Detection Theory predicts when we will
detect weak signals (“hits” to “false alarms”
ratios) in order to try and understand:
– Why people respond differently to the same
stimulus and
– Why the same person’s reactions vary in differing
circumstances
Is it Really a Very Good Study?
• Reliability = Does it provide a consistent result
(even if it is wrong)
• Validity = Does it measure what it says it
measures (Does the steak cause a difference in
the weight shown on the scale?)
• Generalizability (External Validity) = Can we
generalize the results of our study to other
situations and people
Emotion Guided Threat Detection:
Expecting Guns Where There Are None
• Like most quantitative researchers, Jolie
Baumann and David DeSteno (2010) wanted to
conduct and publish a good experimental study.
– Specifically, they hypothesized that emotion (e.g.,
anger as the IV) causes people to perceive an object
as a gun even if it is not a gun
Expecting guns where there are none:
Sensation and emotion affect perception
Stimulus:
Object in a man’s hand
Sensation - Eyes:
Light Waves,
Color, Forms
Perception:
Action:
Press Z key on
keyboard if
gun or press /
key if not gun
The object is a
gun!
…or not.
Emotion:
Angry, happy, or neutral
Accurate
Not accurate
• 84 undergraduates (49 Women, 35 Men)
in partial fulfillment of a course
requirement, were randomly assigned to
one of three groups (Neutral, Angry,
Happy)
Hand-Eye Coordination
Memory Task
Hand-Eye Coordination
Practice Test
Emotion Induction IV
Manipulated DV
A Short Questionnaire
Manipulation Check
The numbers were crunched & the hypothesis was
supported: Angry people are more likely, than happy or
neutral people, to identify an object as a gun when it is
not, but….
• How do we, as critical thinkers, determine whether:
– The measures used in the study are reliable?
– The statements about causality are valid? Does it
measure what it says it measures?
– The results/findings are generalizable?
How do we know whether Baumann & DeSteno used…
• Reliable measurements?
– Emotion induction
• It was a uni- or one-dimensional task [participants had to
write one type of event – neutral, happy, angry] and it’s
easier to interpret one-dimensional tasks.
– “Threat detection” / “Perception Measure”
• Video game, in its computerized presentation of images
for a pre-specified amount of time (750 ms) on a
computer screen, was stable as well as used repeatedly
across several studies since 2002.
– Computers, with their fancy calculations, are generally unbiased,
accurate, precise, and reliable.
• However I do want to point out that this one was
“adapted”…
Aggressive
Action
Tendencies
Emotion
Changed shooting people who are believed to have guns to
clicking a button to identify if the person is believed to be holding a gun
There will be an
increase in
perceptions of
threat for any
generic social
target
So we will only use
White Men as targets
When Stereotypes
& group prejudices
are removed
“Those not
associate
with stereotypes
indicative of
violence”
Given all of that…
Is this a Reliable
measure?
How do we know whether the
statements of causality are valid?
• Where was the experiment conducted?
• We know that experiments conducted in laboratory
settings - where there is more experimenter control
of the setting and independent variables are
manipulated - have higher internal validity.
– Internal validity is about causal control (cause-effect)
– This study WAS conducted in a lab setting
• How were people put into groups?
• Random assignment to groups
– Rules out many threats to internal validity
• Order of measures- Manipulation of emotion 1st,
then computer task
A closer look at internal validity
• The degree of certainty with which statements
can be made about relationships
• How certain are you about the statements:
– Emotion affects our perception of objects.
– Anger causes people to perceive an object as a
gun even if it is not a gun.
• What conditions might affect our level of
certainty?
• Internal validity
– The degree to which causality can be inferred
from a study
• Is the independent variable producing the changes in
the dependent variable?
• Anger (IV) [influences perceptual categorization and]
causes people to misidentify (DV) neutral objects as
guns
Indications that Baumann &
DeStento’s findings are valid
• Random assignment of participants to groups
– Writing about an angry event; writing about a happy
event; writing about a normal day (control)
• Participants thought the experiment was about
memory, not perception
• Two checks regarding specific emotions:
– Emotion apparent in written piece (checked by one
researcher)
– Participants self-reported on a 7-point scale questionnaire
about how they were feeling to see if the writing task
caused participants to select related feelings of anger,
happiness, etc.
– All tasks corresponded within groups AND significantly
differed from the emotions reported in other groups
Indications that Baumann &
DeStento’s findings are valid
• The outcome variable (accuracy calculation of
object identification) was assessed after the
experimental task.
– The order is important. Emotion manipulation
first, then the computerized task of object
identification makes the statement “emotion
affects perception of object” more valid.
Generalizability
(aka External Validity)
• You tell me, are the results generalizable to a larger
population?
• It is difficult to say to whom the result could be generalized
to since we don’t have the demographics of the sample
used
• The results were transferable to later studies, which counts for something
in the research world
•
•
It was a sample of convenience…in fact, it was, in part, a course requirement
to participate in research study
Common practice, but might it affect results? Ideally, researchers need a
sample of a given population where participants are chosen by chance
• Can the results be generalized into an interaction on State St.
• No, but they can support a concept and build a foundation for future
studies to explore this further
• What does our critical examination of the
research mean?
Really Very Good
•
•
•
•
How does this study make you feel?
What did it make you think?
What do you want to know?
What are your hypotheses?
References
Baumann, J. & DeSteno, D. (2010). Emotion guided threat detection: Expecting guns where there are none. Journal of
Personality and Social Psychology, 99 (4), 595-610.
Myers, D. (2014). Exploring psychology in modules (9th ed.). New York, Worth Publishers.
Sanders, L. D. ((2010). Discovering research method in psychology. West Sussex, BPS Blackwell.
Verdugo, E. (1998). Practical problems in research methods: A casebook with questions for discussion. Los Angeles, Pyrczak
Publishing
References
[Untitled illustration of closure]. Retrieved February 17, 2014
from http://brianlande.com/category/culture/
[Untitled illustration of ear]. Retrieved February 17, 2014
from http://www.dizziness-and-balance.com/disorders/bppv/otoliths.html
[Untitled illustration of brain]. Retrieved February 17, 2014
from http://www.ikono.org/category/optical-illusions/
[Untitled illustration of figure ground ]. Retrieved February 17, 2014
from http://www.next.cc/journey/language/figure-ground
[Untitled illustration of depth perception ]. Retrieved February 17, 2014
from http://people.eecs.ku.edu/~miller/Stereo/Section_01/Page_0010.php
[Untitled illustration of a spotted dog ]. Retrieved February 17, 2014
from http://downwiththekids.62stockton.com
References
[Untitled illustration of eye beautiful ]. Retrieved February 17, 2014
from http://www.atelier.net/en/trends/articles/
[Untitled illustration of checkerboard ]. Retrieved February 17, 2014
from http://ocw.mit.edu/courses/brain-and-cognitive-sciences/9-35-sensation-and-perception-spring-2009/
[Untitled illustration of glass half full ]. Retrieved February 17, 2014
from http://www.healthcare-informatics.com/blogs/
mark-hagland/getting-glass-half-full-perspective-healthcare-it
[Untitled illustration of sound wave]. Retrieved February 17, 2014
from http://www.kinoko.us/2013/08
[Untitled illustration of absolute threshold ]. Retrieved February 17, 2014
adapted from http://www1.appstate.edu/~kms/classes/psy3215/Measure/absolute.htm
[Untitled illustration of senses]. Retrieved February 17, 2014
from http://www.gvsu.edu
[Untitled illustration of eye]. Retrieved February 17, 2014
from http://www.iblindness.org/images/eye-diagram.jpg
[Untitled illustration of spotted dog grouping]. Retrieved February 17, 2014
from http://www.blinn.edu/socialscience/LDThomas/MyNotes/08Perception%20&%20Gestalt%20Psychology.htm
Happy http://powertochange.com/wp-content/uploads/2011/01/happyperson.jpg
Angry baby http://powertochange.com/wp-content/uploads/2011/01/happyperson.jpg
Neutal face http://dericbownds.net/uploaded_images/w_unsexy.jpg
Chess Pieces http://mesosyn.com/mental8-8q.jpg