An introduction to attention Peter Knig What is

An introduction to attention Peter König

What is attention Everyone knows what attention is. It is the taking possession of the mind, in clear and vivid form, of one out of what seem several simultaneous 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…. – William James (1890)

Overt attention • Movements of the eyes allow selective aquisition of visual signals. • Other sensory organs equally allow selective capturing of environmental signals.

Selection of signals by sensors

How are salient points selected? • The concept of a saliency map • “Where is the action? ” • Bottom-up approach • But … !

Spotlight of attention • Helmholtz observed that we can enhance perception, if we focus our attention on a location in the visual field. • However, enhancing perception in one part of the visual field takes place at the expense of other areas.

The shadowing task I Condition 1: 65% correct Condition 2: 20% correct

Shadowing task II Somewhere Among hidden the in most the spectacular Rocky Mountains cognitive near abilities Central City is Colorado the an ability old to miner select hid one a message box from of another. Gold. We Although do several this hundred by people focusing have our looked attention for on it, certain they cues have such not as found type it style.

Covert attention

A physiological substrate I

Attentional systems

Plaza Milano

Broadbend‘s filter theory • Early selection. • Selection is based on physical properties of the stimulus (e. g. , pitch, loudness, etc. . . ). • Only one input channel can be processed at a time. • Semantic interpretation only after selection. • Conscious control. • It takes time to shift attention.

Late selection Attended Channel: THE GIRL WAS dogs, six, beach. . . Unattended Channel: world, eight, WAITING FOR HER. . . Reported: THE GIRL WAS WAITING FOR HER. . .

Popout • Popout as pre-attentive processing. The more popout, the later selection!? • Can be trained!

Stroop task red yellow blue green yellow green red blue red green yellow green blue yellow red

But!?

Effects in early visual cortex

Effects of attention

Competing hypothesis • early selection - Broadbent (1958) proposed that physical characteristics of messages are used to select one message for further processing and all others are lost • attenuation - Treisman (1964) proposed� that physical characteristics are used to select one message for full processing and other messages are given partial processing • late selection - Deutsch & Deutsch (1963) proposed that all messages get through, but that only one response can be made (late selection).

The temporal domain V 4

Applications? !

What did we learn / the next time • • Overt/covert attention When: Early, middle, late … What: Spatial … Object oriented attention Where: Areas, -band … Single neurons, Clinical syndromes • How: Saliency maps … Top-down models • Suggested readings: Kastner, Annual Review neurosciences, 2000; JR Anderson, Chapter 3

A definition by exclusion Awake Inattentiveness (drowsy, relaxed) Ignore Asleep Alert Attend Different sleep stages

Popout • • Popout as pre-attentive processing. The more popout, the later selection. T among I and Y vs. T among I and Z. Can be trained!

Covert attention

Treisman’s attenuation theory

What did we learn? • Types of attention – Overt attention, covert attention • What can we attend to – Spatial attention, object based attention - Physical characteristics, semantic contents • Properties of attention • Mechanisms of attention • Why attention

What do we want to know? • • • Types of attention What can we attend to Properties of attention Mechanisms of attention Why attention

Selection by processing stages

Parallel and serial search

Central peripheral cues

Early or late? Treisman and Geffen (1967) set about to test whether the filter was early or late in the processing stream. They had subjects shadow a message on one ear, and tap whenever they heard a certain word in either ear. When the key word appeared in the attended ear, subjects tapped 87% of the time, but when the key word appeared in the unattended ear, subjects tapped 8% of the time. This indicates that early selection is occurring.

Conjunction search

Lesions

Monkey cortex

What can we attend to? Spatially oriented attention vs. Object oriented attention Popout as a pre-attentive mechanism

Change blindness

Selective Divided and divided attention • Attention is studied by • In selective (focused) presenting participants attention tasks, people with two or more are instructed to respond stimuli at the same time. to one input only. • This is called dual-task • In divided attention performance. tasks, people are asked to process and respond to more than one input.

Divided attention • Tracking task. Can track several targets simultaneously.

Dilation in space and time • Expanding dot demo.

Physiological mechanisms • Partiel lobe lesions • Balint‘s syndrome • Attention is a gateway to consciousness.

Covert attention, cortex

Details of parallel search

Problems with spotlight

Spotlight or zoom-lens

Object centered attention

Scaling tuning curves

Neuroscience <-> Psychology what do these examples tell us about the relation between mental phenomena and physical states of the brain? * unrelated ? complete independence -- too many corresponding phenomena * irrelevant ? somehow related, but without any serious implications -- unlikely, because it is possible to influence percepts by affecting neurons (TMS) * correlated ? not independent, but possibly not more than common result from unknown cause -- possible from the above, but perhaps not enough? * causal ? neuronal state determines mental state -- likely in some instances, but applicable to all mental events? is consciousness emerging from neural activity? if we would reach a complete understanding of all brain mechanisms, from the single molecule to the function of extended neural networks, would we be able to comprehensively predict mental states? A. Snyder (Centre for the Mind): Yes

Yet another definition Attention - Attention is what enables us to process information about the world around us. We can only be aware of things around us if we pay attention to them. We can think of attention as a spotlight that we shine on things in the world around us to make them stand out. When something "stands out, " we notice it, bringing it into our awareness, and then process or interpret it. Attention can change rapidly, switching from one thing to another. It can be steered by our intentions ("top-down"), as when we look for a particular face in a crowd, or it can be steered by features of objects in the world ("bottom-up"), as when our attention is grabbed by a police car's flashing lights in our rearview mirror. Preattentive processes help us decide what to pay attention to and what to filter out and ignore. Attention filters and feeds information about the world around us into our minds