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Visual vs verbal imagery

Mental representations of visual and verbal information
Processing of visual (or visuospatial) and verbal information exhibits different properties


Representations of visual information

Change blindness—inability to notice (salient) changes in a visual scene

We might feel that our visual perception captures all the rich details of the environment, but apparently it doesn’t
On one hand, we have a great ability to recognize visual scenes
e.g., Standing (1973): after studying 10000 pictures, participants accurately recognized 8300 of them!


Boundary Extension

When we memorize a visual scene, a wider-angle view of the scene tends to be stored in memory


Two types of representations

When we perceive a visual scene, two types of representations seem to be formed
Representation of the meaning of the scene
Representation of surface properties of the scene (visual details, color, etc.)

The meaning (or the gist) of the scene is very well represented
The surface properties are not


What is attention?

Everyone knows what attention is. It is the taking possession by the mind, in clear and vivid form, of one out of what seem several simultaneously possible objects or trains of thought. Focalization, concentration of consciousness are of its essence. It implies withdrawal from some things in order to deal effectively with others, and is a condition which has a real opposite in the confused, dazed, scatterbrain state.
We often receive more information than we can process simultaneously

In order to use our neural and cognitive resources effectively, it is necessary to select important pieces of information for further processing

This selection mechanism is called “attention”


When does attentional selection occur

There should be a point in the path from sensation to action at which people cannot process all the information in parallel (attentional “bottleneck”)


The filter theory

Sensory information has to pass through some bottleneck

Only some of the sensory information is selected for further processing
The unattended message is usually not remembered
Consistent with the filter theory

However, some information about the unattended message is processed
Some non-semantic aspects of the message (e.g., whether the voice was male or female) are remembered later
This does not support the filter theory


Cocktail party effect

Cocktail party effect
You can hear your name mentioned in a crowded bar, even when you are talking with someone else

Some semantic information can also pass through a bottleneck without attention


Voluntary attention

Top down, goal-directed
Focus of attention is usually the same as the focus of the eyes


Reflective attention

Bottom-up, stimulus-driven
Similar processing enhancement is observed when reflexive cues are used
But only when the target appears soon after the flash (within 50–200 ms)
When more time passes between a reflexive cue and a target, response to the target actually becomes slower

The reflexive attention system has built-in mechanisms to prevent reflexively directed attention from becoming stuck at a location for too long (inhibition of return)


Feature integration theory

People must focus attention on a stimulus before they can synthesize its features into a pattern

In essence, attention works as glue with which various features are combined into an object
Illusory conjunctions of features (e.g., T) occur almost as frequently as correct combinations (e.g., T)

Without focused attention, individual features are perceived but they are not always combined properly


Dual task performance

Can we do two (or more) things simultaneously without having any interference?

The answer to this question depends on the degree to which tasks involved require attention


Stroop effect

Instead, say the COLOR of each word in each column, in a loud voice as fast as you can. The Stroop Effect, named after John Ridley Stroop, is a demonstration of the reaction time of a task and is often used to illustrate the nature of automatic processing versus conscious visual control.