The document discusses the "cocktail party effect", which is our ability to focus attention on a single conversation among other noises. It describes early research by Colin Cherry in the 1950s studying how air traffic controllers distinguish pilot communications. The key challenges are sound separation and directing attention. Later studies showed little semantic information is obtained from unattended messages due to early filtering in the brain. While our understanding of these auditory processes is still limited, factors like expectations and divided attention can contribute to failures in sound separation known as "inattentional blindness."

1. •Were you able to focus your
attention on your intended
target?
•Were you able to listen to
other conversations during the
“Cocktail Party”?

2. • “One of our most important faculties is our ability to
listen to, and follow, one speaker in the presence of
others. This is such a common experience that we
may take it for granted; we may call it ‘the cocktail
party problem’…” (Cherry, 57’).

3. • Cocktail Party Problem- describes the ability
to focus one's listening attention on a single
talker among a mixture of conversations and
background noises, ignoring other
conversations. This effect reveals one of the
surprising abilities of our auditory system,
which enables us to talk in a noisy place.
• The cocktail party phenomenon can occur
both when we are paying attention to one of
the sounds around us and when it is invoked
by a stimulus which grabs our attention
suddenly. Ex: Someone speaking louder than
everyone else or hearing our name.

4. • Colin Cherry- 1953-Early work focused on Air
Traffic Controllers- Early 1950’s
• Several signals coming in from many pilots. Difficult
to distinguish competing sounds from many
environmental sources.

5. • Two important factors and challenges
• 1. Sound Separation- Auditory System helps
separate important individual sounds from
mixture of opposing sounds.
• 2. Directing Attention- Challenge of directing
attention to a sound source of interest, ignoring
the others, and being able to switch attention to
other sources.
• *Listening to two conversations at once
• http://videolectures.net/mlss09us_wang_cppbc/

6. • Sound Separation is an ill-posed perceptual problem
• The brain must infer the correct sounds of interest. What is
important to me as a listener and can I create meaning out of
it? What does it tell me?
• The ear (auditory system) performs a frequency breakdown
on sound signals
• What does figure 2 tell us and what obstacles are present?
• 1. It is not obvious which bits of sound in the mixture belong
to the speech signal of interest (the ‘target’), and which
belong to the other utterances. In many places, the mixture
has energy where the target has little (marked in red in the
right column of Figure 2)

7. • 2. Some of the places where the isolated target speech has
significant energy, one of the other signals has more (marked
in green in the right column of Figure 2).
• These figures show that when the outside sources have
more energy than the target, it is difficult to recover from the
mixture of sounds
• The cocktail party effect works best as a binaural (Bi-Nor-Al)
processing- Two Ears. Species with only one workable ear
are more distracted by outside noises.
• Dan Radke Story- One Workable Ear
• This process is based on the ability of the auditory system to
localize sound sources.
• Once the ear has localized a sound source of interest, it can

8. • Most challenging of the two
• Outside sources compete for a listener’s attention
• Switching between them and ignoring them is difficult
• This can create a cognitive load
• Cocktail Party situations usually demand the full attention of the
listener
• Cherry and later Broadbent used perception and dichotic listening
experiments to test our ability to pay attention to our intended
source.
• Dichotic( DYE-CO-TIC)- relating to or involving the
presentation of a stimulus to one ear that differs in some
respect (as pitch, loudness, frequency, or energy) from a

9. • Subjects were asked to hear and separate different speech
signals presented to each ear simultaneously (using
headphones). –Dichotic Testing.
• http://winstream.creighton.edu/idc24708/winstream.html
• Broadbent- “From the results of his experiment, he suggested
that "our mind can be conceived as a radio receiving many
channels at once": the brain separates incoming sound into
channels based on physical characteristics (e.g. perceived
location), and submits only certain subsignals for semantic
analysis (deciphering meaning). In other words, there exists a
type of audio filter in our brain that selects which channel we
should pay attention to from the many kinds of sounds
perceived”
• Known as Broadbent’s filter theory- “Bottleneck”

10. • 1. Auditory Segmentation is more difficult- Why?
• Visual objects occupy local regions on the retina
• 2. Sound sources are spread out on a frequency map of the
Cochlea (COKE-LEE-A)- Sensory organ of hearing
Result- Sensory representation overlaps more than
visual objects
• 2. Sounds- added in a line to create sound entering ear
• Visual- objects obstruct each other
• Examples: The more people at a party, the harder it is to
hear the person closest to you. This will mask the
speaker of interest
• The speaker’s face will be visible unless blocked by

12. • 1. The voices come from different directions
• 2. Lip-reading, gestures, and the like
• 3. Different speaking voices, mean pitches, mean speeds,
male vs. female, and so forth
• 4. Different accents
• 5. Transition probabilities (based on subject matter, voice
dynamics, syntax . . .)
• 6. Prior knowledge of specific sounds or sound classes
• These are “bottom up” cues

13. • Through the studies very little information about the
unattended message was obtained by his participants
• Physical Characteristics are detected
• Semantics are not
• Unattended auditory information receives very little
processing
• We use physical characteristics between messages to select
which one to attend to.
• The brain is able to use Auditory Scene Analysis (ASA) to do
so- Organize sound into perceptually meaningful events

14. • It is important to understand what we don’t know!
• There is still very much that is unknown about the “Cocktail
party problem”
• Very little has been studied on natural sounds in natural
settings
• In the future, a “top down” approach must be studied that
enhances our knowledge of linguistics, speech acoustics, and
specific sound identities.
• The interaction between auditory attention and sound
segregation has been studied very little and further research
will be needed

16. • Inattentional Blindness- Unexpected objects fail to capture
attention
• Two ways to measure the capture of attention
• 1.Explicit attentional capture- occurs when a salient and
unattended
stimulus draws attention, leading to awareness of its presence.
Ex: Someone says our name or waves at us from a
distance away
• 2. Implicit attentional capture- is revealed when a salient
and
irrelevant stimulus affects performance on another task, re-

17. • Item: An automobile driver looks left down a sidewalk and
pulls forward into a driveway. She hears a thud, looks down
and sees a bicyclist on the ground near her left front fender.
The bicyclist is seriously injured.
• Item: A nurse pulls a vial from a medication cart. She looks at
the label, fills the syringe and then injects the patient. The
patient receives the wrong drug and dies.
• Item: A submarine commander looks through his periscope
and sees no ships nearby. He orders the ballast blown and
the submarine to surface. He then hears the clank of a ship
hitting his deck and realizes that he has surfaced with another
ship directly overhead. The ship overturns, killing 9 people
aboard.
• Item: An Eastern airlines pilot and his fellow officers see a
bulb flash on the control panel. They become so concerned
with the cause, that they don't notice the plane approaching
the ground or hear the alarm. The crash kills over 100 people.

18. • Occurs when we fail to notice an object because our attention
is not focused on it.
• Major cause of human error and accidents
• Everyone is blind at times. Even you MARIA!
• Components
• Most mental processing occurs outside of conscious
awareness
• We experience overload with input
• Our minds are not able to fully process all of the input.
• information stored in memory, or input from the senses, is
processed by a limited-capacity cognitive system

19. • Our brains scan 30-40 pieces of information per second until
something captures our attention!- Limitless
• Our attention filter picks out pieces of information to process.
The rest never reaches our consciousness- Inattentional
Blindness
• This all happens without awareness!
• Cannot be brought under conscious control
• However, the brain is able to fill in the gaps
• 4 important factors that influence attention

20. • 1. Conspicuity (CON-SPI-CUE-ITY)-Capturing of attention:
Falls into two categories sensory conspicuity and cognitive
conspicuity.
• Sensory Conspicuity- Physical properties of information
• Color and Shape
• Automatic process that the brain performs without being
aware of it
• Cognitive Conspicuity- Perceived relevance: What is
important?
• Cocktail Party- Conversation with someone and being able
to hear your name from across the room
• Also occurs with visual meaningful information
-Example: Seeing your first name in the paper

21. • 2. Mental Workload and Task Interference- The more focus on
one task= the less for another
• Blindness is more likely to occur when attention is diverted to
a secondary task
• The more complicated the task, the more attention required!
• Auditory Tasks vs. Visual Tasks
• Less interference when performing an auditory task
(listening to music) and a visual task( watching someone
play baseball)
• More interference when performing an auditory task and
two visual tasks

22. • 3. Expectations- Prior experience and knowledge: What is
relevant?
What is important?
• Confirmation Bias- is a tendency for people to favor
information that confirms their preconceptions or hypotheses
regardless of whether the information is true.
• Errors occur when new and unusual circumstances occur in
familiar situations that we experienced in the past.
• 4. Capacity- Varies from person to person and from within the
same person. Ex: Age
• Example: If someone is under the influence of drugs or
alcohol, their attention capacity will be lower than normal

23. • Capacity Continued
• Extremely difficult to reduce inattentional blindness. Why?
• It is involuntary and unnoticed consequence
• We have the ability to adapt and defend against
information overload
• Solutions
• Increase conspicuity of critical information
• Decrease diversions of attention and secondary tasks when
carrying out complex tasks

24. Conclusions
• Blindness is caused by several factors
• 1. Low conspicuity
• 2. Divided attention amongst various tasks
• 3. High Expectations or low arousal
• Blindness is a natural consequence of our “adaptive mental
wiring”
• We can consciously perceive small amounts of information
and become blind to others.
Videos and Tests!
http://www.youtube.com/watch?v=Zz5yKiHHbs4-
http://www.youtube.com/watch?v=IGQmdoK_ZfY&feature=relat
ed-
http://www.youtube.com/watch?v=Cg8XL0C4ufQ&feature=relat
ed-