Attention

What are transients?

Brief, sudden changes that stand out and grab our attention

When do we not notice transients?

If it is constant (e.g. flickering) or if it is too gradual it might blend in with everything else.

Who experimented with flicker-induced transients and what did they show?

(Rensink, 1997)

• Constant transients (e.g. flickering) can reduce our ability to notice changes

• People struggle to notice changes in a scene when brief blank intervals are used between alternating views

Who experimented with gradual changes?

(Simons, 2000)

• Shows that gradual changes do not capture attention

What is attention?

Refers to processes that select some information and suppresseses processing other information.

Who experimented with the concept of attention as a filter?

(Broadbent, 1958)

• Proposes that humans can only process a limited amount of sensory information at any given time due to an attentional bottleneck

Who experimented with the idea of attention as a limited-capacity resource?

(Kahneman, 1973)

• Showed that our ability to focus on one thing is finite and that we have a limited amount of attention

What is overt attention?

Physically directing your haze towards something

What is covert attention?

Focusing on something without any visible movement or indication e.g. paying attention to something out of the corner of your eye without directly looking at it.

Who experimented with auditory attention and what did they find?

(Cherry, 1953)

• Participants listened to different stimuli in each ear through headphones (dichotic listening)

• They had to focus on and repeat information from one ear while ignoring the other

• The study suggests that covert attention can select information without overt attention and that it's easier to focus on simple features (pitch and volume) but more difficult to focus on high-level semantic features (covert attention selects basic features more easily than complex ones)

What does Broadbent’s filter model (1958) suggest?

It suggests that attention acts as a filter, allowing only certain information through for higher-level processing, while low-level analysis is handled by preattentative processes with large capacity.

What are the advantages to this model^?

It highlights the concept of filtering out excessive information to prevent overload.

Who suggested the concept of attention as an attenuating filter?

(Treisman, 1968)

• Broadbent’s model proposed that ignored information is completely suppressed (message in the non-shadowed ear is not noticed at all)

• Cherry’s research shows that people often notice their own name in the ignored message suggesting that some information is not entirely filtered out

• Treisman suggests that ignore information is attenuated rather than suppressed (weaker processing of it)

What is the spotlight metaphor?

Attention focuses on specific objects of information in the environment while leaving other information in the background.

What are exogenous and endogenous cues?

• Exogenous cues = stimulus-driven, external stimuli that capture attention automatically

• Endogenous cues = voluntary, goal-directed stimuli that guide attention

What are exogenous and endogenous cues in the context of Posner’s cueing paradigm?

• Exogenous cues = location of box flash does not predict target location

• Endogenous cues = arrow tells participants where target is mot likely to appear so they voluntarily move their attention in the direction of the arrow

What were the results of the Posner cueing paradigm?

(Posner, 1980)

• When a cues appears just before the target, people respond faster if the target appears where the cue pointed

• If there is a delay before tha target appears, attention moves away from the cued location, making it harder to respond quickly

• After a long delay, people may even respond slower if the target appears at the cued location (inhibition of return = when the brain avoids focusing on places that have already been cued)

Who showed that attention influences perception (not just responses)?

(Pack, 2013)

• Attention can imporve the perception of unmasked, low-contrast stimuli, particularly when the cue is valid

• Attention enhances how we perceive stimuli, not just how we respond to them

• It doesn’t just increase reaction times it actually helps us focus better

Who showed that attention influences in the human visual cortex?

(Rees, 1997)

• Participants performed linguistic tasks of low or high load while ignoring irrelevant visual motion

• Both brain activity in area V5 (related to motion) and the motion after-effect were reduced during high load tasks, suggesting that the perception of irrelevant distractors depends on the processing load of the main task

How can we measure search processes?

By tracking how quickly people find a target by changing the number of items they have to search through and recording how long it takes them to respond when the target is there or not.

What is the search slope?

It refers to how much the response time increases with each additional item in display.

What is a parallel search?

When the target pops out quickly because it is unique in a feature that is processed early in vision (e.g. its colour). For this, the search slope is ~0 which means that the target is found at the same speed regardless of the number of items

What is a serial search?

When the target doesn’t pop out, observers must shift their attention to each item individually until the target is found. This results in longer RTs and greater / steeper search slopes

What is the difference between determining if something is present or absent?

Search slopes for ‘absent’ are twice as steep because on average, you only need to search half the items to determine if something is present.

Who experimented with both parallel and serial searches?

(Treisman & Gelade, 1980)

• When objects are distinguished by a combination of multiple features, attention must be focused serially

• When a target is unique based on a single feature, it can be found in parallel, but when a target is defined by a combination of features, it requires serial search

What is the feature integration theory (Treisman & Gelade, 1980)?

The brain processes visual features like color and shape separately at the same time, and attention puts them together so we see whole objects clearly.

What is unilateral neglect?

A disorder where individuals ignore the side of space opposite to a brain lesion, and it it associated with damage to the posterior parietal cortex.

Who studied this disorder^?

(Wilson, 1987)

• Administered the Rivermead Behavioural Inatention Test (RBIT) to 28 patients with unilateral neglect and 14 control patients

What is Balint’s syndrome?

It results from parietal lesions in both hemispheres and is characterised by a fixed gaze and simultanagnosia. Individuals with this syndrome can only perceive one object at a time and have difficulty shifting their attention between objects.

What is unilateral extinction?

Where individuals, after brain damage, fail to detect a stimulus presented on the side opposite the lesion when it's presented simultaneously with a competing stimulus on the same side as the lesion.

What can be said about attention as a spotlight?

It may not be effective in the real world and a more efficient approach would be to direct attention to specific objects instead.

Who experimented with the idea that attention selects objects?

(Egly, Driver, & Rafal, 1994)

• RTs were fastest for validly cued targets at the cue’s location

• If attention were a circular spotlight, RTs should have been the same for two types of invalidly cued targets

• But, RTs were fatser when the target was on the same objects, suggesting that attention automatically spreads across the entire cued object

Who conducted the multiple objects tracking task and what did this involve?

(Pylyshyn & Storm, 1988)

• Participants were presented with 8 objects, 4 flash, they all move around, before one flashes up at the end

• The participants must determine if the two flashing objects were the same

• They must track the spotlights with their attention

Who looked at whether we are tracking objects with our attention or with mini spotlights?

(Scholl & Pyshylyn, 1999)

• Vision codes objects as hidden from view (long bars cover the objects), vision codes objects as no longer existing (objects just disappear)

• Concluded that attention does not operate as a spotlight

How does Balint syndrome provide evidence for this too^?

If attention was a circular spotlight, the patients could easily attend to both objects in the same spotlight at the same time (but this is not true).

How can we test for extinction?

By presenting a stimulus bilaterally (on both sides at the same time).

Who experimented with extinction?

(Mattingley, 1997)

• When objects presented unilaterally on the left, the accuracy was 100%

• When they were presented bilaterally, the accuracy decreased significantly

• Tested when the two stimuli appeared on top of the object rather than beside it (effect of space)

• Tested when the stimuli were perceived as a single objects behind a box (effect of objects)

Extinction reflects…

…a competition between objects for attention, which is reduced when only one object is present.

Who also studied these concepts^?

(Conci, 2018)

• Provided more recent findings in support

What does egocentric and allocentric mean?

Do the patients ignore the left side of space (egocentric) or the left of an object (allocentric)?

Who tested this idea^?

(Driver & Halligan, 1991)

• They tested whether people were slower to notice changes on the left or right side of an object

• People had trouble spotting changes on the left side of the object, suggesting their attention was biased toward the right side of space

What is subitization?

The ability to quickly and accurately recognise the number of items in a small set without counting them.

Who experimented with the idea of subitization?

(Jevons, 1871)

• Showed that on average people can immediately tell up to 3 or 4 as quickly as only 1 or 2

• >3-4, some people will have to start counting

Who studied visual long term memory?

(Luck & Vogel, 1997)

• They presented a number of items which then disappeared and either reappeared as the same or some of the items had changed

• This became harder when the set size increased

Who studied whether there is a general attentional limit?

(Cowan, 2000)

• Showed that this is not a fixed number of objects

• Suggested that stimulus complexity and visibility are also important

Why does attention need to select?

• To avoid overloading our perceptual processing

• Even if we process everything, we still need to prioritise which objects control our behaviour

What do early selection theories suggest?

That attention operates early in the visual process to prevent sensory overload and efficiently select based on simple features.

What is the evidence against early selection theories?

• Attention can efficiently select based on simple features, but when trying to select based on high-level features (e.g. word meaning), attention becomes less efficient

• Evidence from primates show attention effects throughout the visual cortex, not just at one early stage.

What are the limitations of early selection theories?

• Suggests that attention only operate after basic analysis, potentially selecting based on simple features (e.g. colour)

• This is inefficient and not true

Who studied eye movements?

(Yarbus, 1967)

• Presented participants with an image and looked at their pattern of eye movements

• The pattern might be due to more salient parts of the image

• They showed the image again and asked questions to the participants

• Suggested that eye movements are not random but are well-targeted (might be better explained by late selection theories)

What does subsequent visual search findings suggest?

That parallel processing is more complex than previously thought

Why does attention occur later?

To ensure that the correct objects guide actions

What do late selection theories propose?

That attention operates after all sensory information has been processed.

Who studied high-level parallel processing of multiple items?

(Shiffrin & Gardner, 1972)

• They found that people could process 4-letter stimuli just as accurately when shown all at once as when shown two at a time, suggesting limited but parallel processing capacity (though only with a small number of items)

(Raymond, 1992)

• Showed that focusing on one target briefly makes it harder to notice a second target that appears soon after - an effect called the attentional blink

What can we conclude about when attention selects?

It selects at different stages of processing for different reasons

What is the purpose of early selection?

It can minimise the influence of irrelevant information when a stimulus comprises of many items