Lecture 2: Attention Flashcards
• The Meaning of “Attention”
Brain’s ability to self-regulate input from the environment (a lot of sensory experience which we are not processing, we select and prioritise)
two types of attentions
- Sustained Attention (Alertness)
> Related to psychological arousal (continuum from drowsy, inattentive to alert, attentive)
> Problem of vigilance: performance declines over a long watch (radar operators, quality control inspectors, etc.)
II. Selective Attention (this subject)
> Limited in the number of stimuli we can process
> Attend to one stimulus at the expense of others
> People as limited capacity systems: don’t treat all stimuli equally
What is the Cocktail Party Problem?
- How do we follow a conversation in a crowded environment?
- Can “pick out” one conversation from background while excluding others
- “Picking out:” processes take sound energy at ear, translate to understanding
- Translation is selective (stimuli not all treated equally - not just loudness or volume based)
What did Cherry study? How?
what happens to unattended messages?
Dichotic Listening - Two passage of continuous speech to each ear using stereo
Shadowing - repeating the passage out loud as it occurs to ensure that people are attending to the attended channel
What were Cherry’s findings?
- Shadow Message 1, then ask about contents of Message 2
- Unattended Channel: No memory for unattended message
Did people process anything of the unattended channel in Cherry’s studies?
- NO
- Switch from English to German
- YES
- Switch from male to female
- Switch from voice to 400 cps pure tone
- Something queer
- Reversed speech
What happends to unattended message?
> Only superficial (physical) features perceived - (things distinguishing voice, non-voice, or male, female)
> Semantic content not analysed (language, meaning)
What can cognitive processes be divided into?
Preattentive processes
> run off automatically, stimulas dirven, sensory physical features processed preattentively (regardless of whether we are attending or not)
Focal attention (required for meaning)
• How did Cherry study how We Select the Attended Message? (how do we solve the cocktail party problem?)
- by using Binaural presentation (Cherry): both ears receive both messages, same voice, differ only in content
- Requires a shadowing task
- Very difficult! Requires shadowing for ~20 trials to be become reasonably accurate at the message
- lose - the ability to locate the sound in space (by using phase differences in arrival times at ear)
- therefore - conclusion - we select an attended message by locating the sound in space or distinguishing features (such as male vs female voice)
what are Criticism of Cherry?
- Interested in what’s perceived, Cherry looked at what’s remembered
- Confounds perception and memory
- May be perceived then forgotten?
explain the filter theory by Broadbent 1958.
- Attention acts as a filter to select stimuli for futher processing
- Meaning from sound is extracted in limited capacity channel
- Filter precedes channel, protects it from overload
- All stimuli stored briefly in short term store (STS) - in between senses and selective filter
What is the short term store?
> Raw acoustic trace, decays quickly if not selected
> similar to echoic memory
Why did Broadbent agrue that the short term store is critical to the operation of the filter?
Split-span expirment
People recall more digits if they do it ear-by-ear rather than temporally because the STS memory trace is trasient and decays quickly (<.5s) and switches in filter takes time - Ear-by-ear recall needs 1 filter switch, 5 switches needed to follow temporal order (STS trace decays)
what are the conclusions of filter theory?
- Attentional selection based on simple physical features (location in space, voice, etc.)
- Simple physical features extracted preattentively (don’t require access to limited capacity channel)
- Meaning requires access to limited capacity channel, only extracted if stimulus is attended
How did filter theory fail?
“Dear Aunt Jane” experiment (Gray & Wedderburn, 1960)
> Split-span experiment with meaningful material
L ear: Dear Three Jane
R ear: Six Aunt Five
The preferred recall order was Dear Aunt Jane and Six Three Five –> follows sematic context not presentation ear (not as in Broadbant’s experiment ear-by-ear to minimise switches)
Filter theory says shouldn’t be able to do this, because the filter acts before any meaning is extracted (how can filter change the read out strategy?)
