Unit 3 - Sensation & Perception - Moore Public Schools · 2019. 7. 24. · Unit 3 - Sensation &...
Transcript of Unit 3 - Sensation & Perception - Moore Public Schools · 2019. 7. 24. · Unit 3 - Sensation &...
Unit 3 - Sensation & Perception
Chapter 4 Part 1: Intro. to S & P
Today’s Goals
●Can you:
○Define sensation and perception
○Discuss basic principles of sensory
transduction, including absolute threshold,
difference threshold, signal detection, and
sensory adaptation.
○Explain the role of top-down processing in
producing vulnerability to illusion.
Sensation & Perception
How do we construct our representations of the
external world?
To represent the world, we must detect physical
energy (stimulus) from the environment and convert it
into neural signals, a process called sensation.
When we select, organize, and interpret our
sensations, the process is called perception.
What do you sense? In this
case, what do you see?
What do you perceive?
Bottom-up Processing
Analysis of the stimulus begins with the sense receptors
and works up to the level of the brain and mind.
Knowing that the bottom middle flag is the American flag is due to bottom-up
processing…your senses break down the flags into colors, shapes and
lines…which you then process and organize to figure out which is the
American flag.
Which of the following is the American flag?
Top-Down Processing
Information processing guided by higher-level mental
processes as we construct perceptions drawing on our
experience and expectations.
Y-u c-n r-ad -hi- se-te-ce -it-
ev-ry -hi-d l-tt-r m-ss-ng.
The reason you can…is top-down processing! Your expectations
and experiences let you fill in the blanks by making inferences on
what you think “should” be there!
Bottom-up and top-down processing work
together to help us sort out complex images.
Making Sense of Complexity
“The Forest Has Eyes,” Bev Doolittle
Thresholds
Absolute Threshold: Minimum stimulation needed
to detect a particular stimulus 50% of the time.
Difference Threshold: Minimum difference between
two stimuli required for detection 50% of the time,
also called just noticeable difference (JND).
Weber’s Law
The size of the JND is proportional to the intensity of the
stimulus
●if the stimulus intensity is high, the JND will be large
(or it will take a bigger increase to notice the difference)
●if the stimulus intensity is low, the JND will be smaller
(or it will take less of an increase to notice the difference)
Subliminal Threshold
When stimuli are below
one’s absolute threshold for
conscious awareness.
In other words…for most
people these items are not
consciously detected.
HOWEVER…it is possible
that some will notice these
items!
Examples of “subliminal” messages in
advertisements…
In the spring/summer of 1990, Pepsi
distributed a line of “Cool Cans” as
part of a promotional campaign.
All 4 of them are shown below…
…the 2nd “NEON” can apparently
had an “embedded” message if you
stacked two cans together..http://www.snopes.com/business/hidden/coolcans.as
p
http://www.tombihn.com
/
Info from…http://www.snopes.com/business/hidden/tombihn.asp
An embedded “subliminal”
message was found in 2004 on the
french translation portion of a care
tag on Tom Bihn backpacks/laptop
cases/briefcases…
What does it say????
“We’re sorry our president
is an idiot. We didn’t vote
for him.”
Many people viewed this
as a slam against
President Bush…the
company maintains that it
is a joke between a
seamstress and the CEO.
During the 2000 Presidential campaign…the following ad
was run nationally on TV by the Republican party…
Bush campaign ad controversy…
The Democratic party claimed that
the Republicans were trying to use
“subliminal” messages to influence
the national public…so they asked
the FCC to investigate the TV ad!
The ad's creator calls the word's appearance a "visual
drumbeat" meant to grab viewers' attention and not an
intentional message. It was supposed to be an abbreviated
version of “bureaucrats”… Bush also said “rats” ad not
meant to be a subliminal message
Subliminal Messages…Backmasking?It is recording technique in which a sound or message is recorded
backward onto a track that is meant to be played forward.
This is a deliberate process…currently the technique is being used to
censor words or phrases for "clean" releases of songs.
Backmasking was popularized by The Beatles, who used backward
vocals and instrumentation on their 1966 album Revolver.
The Backmasking has been a controversial topic in the US since the
1980s, when allegations from Christian groups of its use for Satanic
purposes were made against prominent rock musicians, leading to
record-burning protests and proposed anti-backmasking legislation by
state and federal governments.
Whether backmasked messages exist is a debate, as is whether
backmasking can be used subliminally to affect listeners.
Background…
● initially gained worldwide fame in the early 80s as “backmasking” in
music
●the pioneer of this field is Australian, David John Oates
What is reverse speech?
● idea that if human speech is recorded and played backwards, mixed
amongst the gibberish at regular intervals can be heard very clear
statements
●statements are usually short and relate to the content of the
forward speech
●believed to be a natural part of our speech processes
●Oates believes that the reverse speech is our unconscious mind
finding a “voice”
○for example…if telling a lie in forward speech, in reverse the
truth may come out
Subliminal Messages…Reverse Speech?
Some examples of reverse speech….
“I surely would fit in”
You will hear the “forward” message 1st…followed by 3 “reverse”
messages (1 at regular speed and 2 at slowed speeds).
Can you figure out what is being said???
“See the dream” “Soon I’ll beat the law”
For more examples visit…http://www.reversespeech.com/home.htm
Studies have found that subliminal words
flashed briefly on a screen can “prime” a
person’s later responses…but will not impact a
large group’s buying habits!
Do the previous items really constitute
subliminal messages?
Do subliminal messages really influence
our behaviors?
Signal Detection Theory (SDT)
Predicts how and when we detect the presence
of a faint stimulus (signal) amid background
noise (other stimulation). Assumes that there is
no single absolute threshold and detection
depends on:
●Person’s experience
●Expectations
●Motivation
●Level of fatigue
JOE!
Signal Detection Theory (SDT)
Presence of Stimulus
Yes No
De
tectio
n o
f S
tim
ulu
s
Ye
sN
o
Sensory Adaptation
Diminished sensitivity as a consequence of
constant stimulation.
Put a band aid on your arm and
after a while you don’t sense it.
After you initially get into a pool,
it no longer feels cold.
Let’s test the idea of sensory adaptation…
Sensory Adaptation – Marker Test
Number your paper to 12…
Each time I tell you to “SMELL”,
please quickly sniff your marker and
quickly rate the
INTENSITY OF THE AROMA
on a scale of 1 – 20(1 = very slight smell 20 = very strong smell)
What happened over the various trials?
Quickly switch markers with your neighbor and rate the
intensity of the aroma of their marker…