•Were you able to focus your attention on your intended target?

•Were you able to listen to other conversations during the “Cocktail Party”?

•What was going on? Any Ideas?

Cocktail Party Problem

• “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’).

• 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.

Early Work• 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.

Fundamental Principles• 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 /

Why are these Problems?• 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)

Continued• 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

extract signals of that source out of other competing sounds.

2nd Problem- Attention Selection• 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 stimulus presented to the other ear.

Testing• 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”

Visual vs. Auditory Differences• 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 hearingResult- 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 something else

Solutions and Perceptual Mechanisms-Cherry• 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

Cherry’s Conclusion• 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

Understanding• 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

Monkey Business• 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-gardless of whether or not subjects are aware of the stimulus.

Examples• 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.

Blindness• 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

Attention- How does it work• 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

• 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

• 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

• 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

• 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

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=related- http://www.youtube.com/watch?v=Cg8XL0C4ufQ&feature=related-http://www.youtube.com/watch?v=voAntzB7EwE&feature=related