Attentional Blink

Question 1

What is the attentional blink?

Answer 1

• Something can be made invisible by showing it quickly then something else of more significant
• Discovered by Jane Raymond + Kim Shapiro

Question 2

Key Features of the Attentional Blink

Answer 2

• Rapid visual stimuli (at ~10 Hz)
• Participants asked to look out for
  TWO targets and report if they saw
  them at the end of each trial
• The first target is referred to as T1, and the second target as T2
• Masks (i.e. distractors) need to follow T1 and T2 for the effect to work

Question 3

What happens to the T2? - The N400

Answer 3

When your brain accesses the
meaning of a stimulus => a
negative event-related potential, the N400
* This reflects cognitive processes related to accessing the meaning (semantics) of a stimulus
* To see if the brain processes meaning of T2…
* We can use the N400 as a sign that someone’s brain is
processing meaning, without relying on participants’ saying so

Question 4

Experiment with Attentional Blink - Luck et al. 1996

Answer 4

Classic AB to T2 – i.e. the word ‘cat’ is less likely to be seen when
shown 300ms after T1
* BUT the N400 is pretty much the same size regardless of time since T1
* Therefore, even if you don’t know that you saw T2, your brain still did
some processing of what it means

Question 5

Theories of the AB - Interference Theory (Shapiro et al, 1994)

Answer 5

T1, T2, and their masks (=distractors) are all encoded into a temporal buffer – e.g. visual short-term memory
- The AB is competition for retrieval among all items in short-term memory

Question 6

Evidence for interference theory - Isaak et al 1999

Answer 6

Reported that the AB increases with increasing numbers of task-irrelevant competitors (distractors)

Question 7

Theories of the AB - Unified Model

Answer 7

• Due to the mask following T1, increased attention is required to
  process T1
• This leaves less attention for processing of T2, which leaves T2
  vulnerable to decay or interference from distracters