Lecture 5 - Stimulus processing (Cognitive Neuroscience, UU)

Attention is selective. Selective attention refers to the allocation of processing resources, generally at the expense of resources allocated to other stimuli.

Neuroscientific concept: attention is the manipulation of activity of population of cells that process sensory information.

Advantages of attention:

• Detailed representation of stimuli
• Faster and more accurate response to stimuli
• Better memory of stimuli, better decision-making, etc.

Disadvantage: opposite effect for unattended stimuli.

Arousal is not attention. Arousal modulates all sensory signals  baseline effect

Attention selects and modulates specific sensory signals  selection effect

Two forms of attention:

• Overt attention: you look at what you want to attend
• Covert attention: you attend something that is outside your gaze

Internal manipulation of attention: you decide yourself what you attend. This is endogenous, top-down or controlled attention.

External manipulation of attention: sensory stimulus characteristics decide what you attend. This exogenous, bottom-up, reflexive attention. The sensory area is shaped by experience over years. It responses to most relevant things due to experience.

--> Salience models: models that predict what you attend automatically.

Attentional blindness

• You cannot process everything at the same time: loss of information.
• Can be measured using the change blindness paradigm

Attentional blink

• Try to detect the white target
• As you are busy with target 1, target 2 is missed

Attentional cueing

• Posner’s cueing task
• Recognition of target is better and faster for congruent cue, and worse for the incongruent cue
• Same applies to exogenous cue

Cocktail party

• People prefer one auditory stream of information over another
• Ignoring one stream is called shadowing

Visual search

• Quickly finding an item in a clustered environment

Neural mechanisms are strengthened when attention is given to it.

Question 1 can be answered using EEG: great temporal resolution.

• Also auditory attention: compare ERP to attended vs. unattended stimuli
• BER is unaffected by attention
• P20-50 and N1 are evoked by attention

Attention is necessary for similarity analysis.

Mismatch negativity (MMN): oddball paradigm.

Feature attention: the amplitude is increased for attended stimuli and the sensitivity is narrowed.

--> Attention acts in the brain area that codes the target feature.

• Orientation: V1
• Color in V4
• Motion in MT+
• Faces in FFA
• Pitch/frequency in auditory cortex

Spatial attention: attention to location in a visual field. Could be an auditory source.

Receptive field: area of interest to the neuron. A neuron responds when a stimulus is shown in its receptive field.

Each cell has a receptive field: responses only to a specific area in the visual field.

Object attention: also known as object-based attention.

Object or spatial attention is guided by features.

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