05/05/2012 by admin.

If we look at how communication works we find that words and phrases have a great influence on attention. They bring into the consciousness of the listener the concepts that are uttered. This is what meaning is – the concepts that a word or phrase can steer attention towards. This is what communication is – the sharing of attention by two (or more) brains on a sequence of concepts.

So it is not surprising that it is useful to talk to oneself. What we are doing when we self-talk is to steer our consciousness. In recent paper (see citation below), Lupyan and Swingley look at how self-directed speech affects searching. Here is part of their conclusions:

In this work, we examined effects of self-directed speech on performance on a simple visual task. Speaking the name of the object for which one was searching affected performance on the visual search task relative to intermixed trials on which participants read the word but did not actually speak it before or during search. The effect of speaking depended strongly on the characteristics of the target item. Search was improved for the most familiar and prototypical items - those for which speaking the name is hypothesized to evoke the visual representation that best matches the visual characteristics of the target item. Search was unaffected or impaired as the discrepancy between the name and target - measured by measures of familiarity and imagery concordance - was increased.

Facilitation due to speaking also became larger with repeated exposures to the target items. Arguably this occurred because multiple exposures strengthened the associations between the label (e.g., “elephant”) and the visual exemplar (a given picture of an elephant). The idea that saying a category name activates a more prototypical representation of the category is also supported by the finding that speaking the name actually hurts performance for items with low within-category similarity. One implication is that repeating the word “knife” may, for example, help an airport baggage screener spot typical knives, but actually make it more difficult to find less prototypical knives.

On our view, the reason speaking the target name affects visual search performance is that speaking its name helps to activate and/or keep active visual (as well as nonvisual) features that are diagnostic of the object’s category, facilitating the processing of objects with representations overlapping those activated by the label. This activation of visual features occurs during silent reading as well. Indeed, it is what allows fore-knowledge of the target to guide search. Self-directed speech, as implemented in the present studies, is hypothesized to further enhance this process.

This idea of controlling attention is also shown when people try to keep some piece of information in working memory by repeating it, when they encourage themselves to do something difficult or scaring, when they are learning (or planning) a complex sequence of actions. Searching is not the only activity that benefits from a little talking to yourself.

Lupyan, G., & Swingley, D. (2011). Self-directed speech affects visual search performance The Quarterly Journal of Experimental Psychology, 1-18 DOI: 10.1080/17470218.2011.647039

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26/04/2012 by admin.

I have been interested in communication for many years. Not written stuff but oral speech and accompanying non-verbal communication. How is it that we manage a link, a synchrony, a shared perception between two minds.

A recent blog posting in the Scientific American has some interesting things to say about movies, similar to what has been said about stage magic. There are ways to affect the audience and are skilled practitioners of these arts. Here is the link to Maria Konninova’s posting, The Innate Irresistibility of Film.

Of course we start out with a perceptual slight of hand. The movie is discrete frames but we see it as a continuous. This is because the frames per second is close to the natural ‘frames’ of consciousness which is also discrete. Konninova also mentions the control of blinks, eye movements and event breaks.

… researchers are finally beginning to understand what it is that makes the present-day film experience so binding on a profound level - and why it’s often difficult for older movies to keep up. It seems that filmmakers have over the years perfected the way to best capture - and keep - viewers’ attention. Through trial, error, and instinct, Hollywood has figured out how best to cater to the natural dynamic of our attention and how to capitalize on our naïve assumptions about the continuity of space, time, and action.

… blink synchronicity: if we see someone blink, we’ll likely blink right along with him. Film editor Walter Murch noticed that very thing when he was editing Francis Ford Coppola’s The Conversation. When Gene Hackman blinked, there went Murch’s eyes—and that’s precisely where he wanted to place the film cut. Cut at the blinks, and more likely than not, the viewers will perceive the action as continuous. The cut itself will go unnoticed. … People who view the same film tend to synchronize their blinks – and that synchronization reflects the editing of the story. …

When people watch a movie, their eyes tend to follow similar patterns. Even if a scene has no actors, it remains likely that gaze focus will follow the same trajectory between different viewers. And it’s not just the gaze: each viewer’s brain may actually be reacting in similar fashion as well.

In one study, individuals watched the first 30 minutes of The Good, The Bad and the Ugly while their brains were scanned by fMRI. Researchers found that 45% of neocortical activity—including areas implicated in vision, hearing, emotion, language, and multisensory integration—was quite similar for each viewer. That’s almost half the activity of that part of our brain that coordinates our higher cognitive functions. Impressive indeed.

… When people viewed The Red Balloon in a scanner and then divided the film into events, cuts that coincided with significant changes in action predictably activated dorsal frontal and medial temporal areas of the brain—associated with attentional control and motion processing, respectively—in a similar fashion for each viewer.

In the same way that we could learn much about attention from magicians, we could learn much about consciousness from movie editors. Back to the subject of communication, we can also learn from ordinary conversations. It seems that people who are busy talking seem to get on the same wave length. They synchronize their movements and posture, they get a rhythm going in the speech, their mimic each other’s face expressions, they blink together. Hey, they are coordinating their consciousness.

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23/04/2012 by admin.

I have long thought of the thalamus as the ‘grand central station’ of the brain. An extension of the spinal cord (the reticular formation) comes through the lower brain and ends in the thalamus. It is the ascending reticular formation that controls consciousness – when it is active, we are aware and when it is quiet, we are not aware. The signals that keep us awake come from the brain stem up the reticular formation into the thalamus, at the thalamic reticular nucleus. The parts of the thalamus seems to be connected to everything else too. It sends signals and receives signals from every part of the cortex and these signals are essential for consciousness. It has input from all the senses which it feeds on to the cortex (bar smell which mostly goes straight to the cortex and reaches the thalamus via the cortex). The thalamus communicates with the basal gangia and receives information on motor commands through them. And on it goes; there seems to be little that does not involve the thalamus directly or indirectly.

Basilis Zikopoulos and Helen Barbas have a series of papers on attention that put the gate to attention in the thalamic reticular nucleus. We have attention that is top-down and centered on the current task, bottom-up and centered on novel sensory input. They imply that there is also attention centered on strong emotional inputs. The thalamic reticular nucleus inhibits contributions to attention. It receives input from the amygdala (the emotional center) and if this is intense, other potential objects of attention are inhibited. The frontal cortex gives input to the same area and may trigger the inhibition of other potential objects of attention to give top-down attention. Input in the same area from the thalamic mediodorsal nucleus may serve the same purpose for bottom-up attention. The strength and priority of these signals would be used by the thalamic reticular nucleus to drive the spotlight of attention.

Here is the abstract from Zikopoulos and Barbas’ recent paper, Pathways for Emotions and Attention Converge on the Thalamic Reticular Nucleus in Primates, in the Journal of Neuroscience:

How do emotional events readily capture our attention? To address this question we used neural tracers to label pathways linking areas involved in emotional and attentional processes in the primate brain (Macaca mulatta). We report that a novel pathway from the amygdala, the brain’s emotional center, targets the inhibitory thalamic reticular nucleus (TRN), a key node in the brain’s attentional network. The amygdalar pathway formed unusual synapses close to cell bodies of TRN neurons and had more large and efficient terminals than pathways from the orbitofrontal cortex and the thalamic mediodorsal nucleus, which similarly innervated extensive TRN sites. The robust amygdalar pathway provides a mechanism for rapid shifting of attention to emotional stimuli. Acting synergistically, pathways from the amygdala and orbitofrontal cortex provide a circuit for purposeful assessment of emotional stimuli. The different pathways to TRN suggest distinct mechanisms of attention to external and internal stimuli that may be differentially disrupted in anxiety and mood disorders and may be selectively targeted for therapeutic interventions.

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18/03/2012 by admin.

I once had a very boring task that was part of my research (to do with rayon chemistry not the brain). I have never done anything as boring before or since. I had to time how long it took for 100 drops to fall from a tiny hole. So I had to keep a count without losing my place and I had to see and register each drop. It usually took between 5 and 10 minutes for 100 drops to fall. The problem was that there was no rhythm. There might be 2 mins between a pair of drops or there could be 3 or 4 drops almost touching one another. This meant that my whole attention was taken up with watching and counting. I could not let my mind wander at all. After a run, I was worn out with fatigue and had to recover before I could face another run. I often failed in this simple (mindless) procedure and ended up not knowing where I was in the count or whether I had see the last drops. I was only using a tiny bit of my brain and forcing the rest to sit quietly and not even ‘drum its fingers’. An item in ScienceDaily reminded me of that long ago task. (here)

Levinson, Smallwood and Davidson looked at the relationship between working memory and attention. When the task does not use all of someone’s attention – how do they use their idle resources?

The researchers asked volunteers to perform one of two simple tasks, either pressing a button in response to the appearance of a certain letter on a screen, or simply tapping in time with one’s breath - and compared people’s propensity to drift off… People with higher working memory capacity reported more mind wandering during these simple tasks, though their performance on the test was not compromised…. What this study seems to suggest is that, when circumstances for the task aren’t very difficult, people who have additional working memory resources deploy them to think about things other than what they’re doing.

Interestingly, when people were given a comparably simple task but filled with sensory distractors, the link between working memory and mind wandering disappeared. Giving your full attention to your perceptual experience actually equalized people, as though it cut off mind wandering at the pass….In essence, working memory can help you stay focused, but if your mind starts to wander those resources get misdirected and you can lose track of your goal. Many people have had the experience of arriving at home with no recollection of the actual trip to get there, or of suddenly realizing that they’ve turned several pages in a book without comprehending any of the words. It’s almost like your attention was so absorbed in the mind wandering that there wasn’t any left over to remember your goal to read.

Where your mind wanders may be an indication of underlying priorities being held in your working memory, whether conscious or not. But it doesn’t mean that people with high working memory capacity are doomed to a straying mind. The bottom line is that working memory is a resource. If your priority is to keep attention on task, you can use working memory to do that, too. (But it can be very tiring, I remember.)

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20/02/2012 by admin.

Christopher Bergland (here) believes that we think in a different way when we exercise.

Anyone who exercises regularly knows that your thinking process changes when you are walking, jogging, biking, swimming, riding the elliptical trainer, etc. New ideas tend to bubble up and crystallize when you are inside the aerobic zone. You are able to connect the dots and problem solve with a cognitive flexibility that you don’t have when you are sitting at your desk. This is a universal phenomenon, but one that neuroscientists are just beginning to understand. … Creativity is the ability to bring together disparate ideas in new and useful combinations. What is happening to the electrical, chemical and architectural environment of our brains when we exercise that stimulates our imagination and makes us more creative? What is the parallel between the waking dream state induced by exercise and the REM dream state experienced during sleep? Although these questions remain enigmatic, neuroscientists have identified that the non-thinking ‘default state‘ of consciousness is key to creative thinking. … Sweat is like WD-40 for your mind-–it lubricates the rusty hinges of your brain and makes your thinking more fluid. Exercise allows your conscious mind to access fresh ideas that are buried in the subconscious. Every thought that you have is a unique tapestry of millions of neurons locking together in a specific pattern-this is called an engram. If you do not ‘unclamp’ during the day, you get locked into a loop of rut-like thinking. If for any reason you are unable to do aerobic activity, focused meditation is also an excellent way to create a default state.

The piece has quotes from a number of writers and runners such as:

Ralph Waldo Emerson said of Thoreau: “The length of his walk uniformly made the length of his writing. If shut up in the house, he did not write at all.”

I find this idea intriguing. There is no reason why the rhythm and effort of running (or even walking) would not affect both cognition and consciousness. There might even be some chemistry there. But also the ‘default network’ angle is interesting. If the motor part of the brain is busy and, because of moving, we cannot override the control of sensory input – then there cannot be a ‘task’ control of attention. It would be, or be like, the default network being in control.

A totally opposite but somehow the similar effect is my old trick of sitting still in the dark and silence to think. What would be the difference between: the motor and sensory parts of the brain working automatically and therefore leaving the rest of the brain free to mull; and, a sort of imposed sensory deprivation and motor inactivity letting the brain mull? Maybe or maybe not. I mention this for those of you who are like me and too old and sore to ever run again.

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17/02/2012 by admin.

Two sorts of perceived items must compete for attention: items that are required for on-going tasks and items from the environment that are surprising or very conspicuous. We do not want to be hit by a bus because we are solving a little problem, nor do we want to be distracted from our concentration by every little change in our surroundings. How is the compromise accomplished?

In a recent paper (see citation) Mazaheri and others have studied this question. They used tracking of eye movements and EEG recordings to follow the choice between a target that was part of the ‘task’ and a distraction (one of: none, a distraction that was no more conspicuous than the target, and a highly conspicuous distraction). Would the eyes cascade towards the target or the distraction first? And was there a difference between the EEG events before a move towards the target compared with one towards the distraction?

Not too surprisingly, we found that people differed in their ability to concentrate and ignore the distraction. Despite this there was a clear pattern of activity. When there was distraction there appeared to be a prior disengagement from the task.

We found that an increase in pre-stimulus alpha activity over frontal-central regions was predictive of subsequent attentional capture by a salient distractor. Previous studies have found an alpha increase in a particular region to be indicative of the functional inhibition/disengagement of that region. … could reflect the disengagement of the frontal-eye fields (FEF). FEF is involved in top-down voluntary control of saccades and attention.

Also there was a decrease in the N1 wave response when the target won over the distractor for the first saccade. This is assumed to be due to a gating that favours items at the current spatial focus. An increase in N1 would imply greater task-relevant processing locked to the appearance of the stimulus in the trials where the target was looked at first.

As well as this locking effect tied to the stimulus (a fixed time after the stimulus appeared), there is also locking tied to the saccade (a fixed time before the eyes moved).

there was a central-parietal alpha burst just preceding the onset of the first saccade that was greater in amplitude for saccades to the target. … could index the transient inhibition of the prepotent response to saccade to the more salient distractor. … intraparietal sulcus contains an attentional priority map and is involved in saccadic control and is a good candidate for being the source of the inhibitory control signal seen here.

They also found evidence of a locking effect of a negative wave occurring before the eye movement.

A qualitative inspection of the saccade locked ERPs (event related potentials) suggests that this negative deflection is due to a latency shift in the slow negative drift building up to a potential preceding the saccade to a salient distractor.

It would be interesting to see how these indications varied if the task targets and the conspicuous distractors had varying importance/strength. What does it take for the top-down control to overcome bottom-up and vice versa?

Mazaheri, A., DiQuattro, N., Bengson, J., & Geng, J. (2011). Pre-Stimulus Activity Predicts the Winner of Top-Down vs. Bottom-Up Attentional Selection PLoS ONE, 6 (2) DOI: 10.1371/journal.pone.0016243

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05/02/2012 by admin.

Don’t think of a purple elephant – you know the game. It is practically impossible to manage this seemingly simple task. We will think about the suppressed thought, probably every minute or so. Why?

In fact, the more seriously we put effort into avoiding the thought, the more it comes to consciousness. In order to avoid the thought, we have to keep monitoring whether the suppression is working. We, in effect, keep asking ourselves whether a purple elephant is anywhere near our consciousness. Every once in a while, that unconscious monitoring pops the thought into consciousness.

This sort of mechanism can explain some social gaffs and freudian slips. We are just trying too hard to avoid certain subjects/words. If we were less nervous about those subjects it would be easier to avoid blurting out the unacceptable remark we are determined to avoid. I think some people call this ‘don’t mention the war’ effect after a famous Fawlty Towers episode.

I heard a story of someone trying to learn to ride a bicycle. They were finally staying upright and feeling pretty good. After a few moments there was a post along the path and they concentrated on avoiding it. The more they told themselves to avoid the post, the more they were aimed at it and in the end hit it (dead center).

What comes into the center of consciousness is what is important either because it was not predicted (a surprise) or because it is part of the on-going task we are trying to accomplish. Usually these are referred to as bottom-up and top-down steering of attention. We have to be careful not to turn a no-no thought into a top-down focus of attention.

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10/12/2011 by admin.

Attention and consciousness are often thought to be inseparable or even two words for the same thing, but under unusual circumstances they can be separated. It is not easy to separate them and so what consciousness does to assist attention would be an important function of consciousness to the extent that attention was important to survival. Well that’s a no brainer – all you have to do is not attend to what is happening when cross a busy road to understand the risk to survival of not attending to the important things. Surely this function alone would pay the biological cost of consciousness.

Consciousness, in effect, is a canvas on which the spotlight of attention can fall so that all areas of the brain can know what is currently important and so that part of the canvas can be rendered in more detail. What steers the spotlight? We have mechanisms to keep the brain focused on a task or goal, thought of as top-down control, and mechanisms to shift focus to unusual or alarming sensory input, thought of as bottom-up control. This keeps what is significant in awareness and available to the whole brain. All the resources of the brain can be brought to the important problem of the moment. Because what is currently significant is in consciousness, it is also in memory. We start memories with the most important aspect of each consecutive moment.

Victor Lamme and his group have studied attention and consciousness with, to my mind, a very reasonable attitude – forget introspection etc. and let the neurological evidence rule. Looking at the neural correlates of consciousness – the fast forward wave and the feedback wave with its synchrony across large areas of the cortex – and controlling the visual stimulus, they find the following.

Because depth of processing (attention) and the fast forward sweep (FFS)/ recurrent processing (RP) distinction are orthogonal, a visual stimulus can reach any of four stages of processing:

• Stage 1: Superficial processing during the FFS; This would happen when a stimulus is not attended and is masked. Unattended and masked words, for example, do not activate word-form selective areas, only visual areas, so do not even penetrate deeply into the ventral stream hierarchy.

• Stage 2: Deep processing during the FFS; for example, a stimulus that is attended, yet masked (and hence invisible). This stimulus does travel through the whole hierarchy of sensory to motor and prefrontal areas, and may influence behavior, as in unconscious priming.

• Stage 3: Superficial processing of a recurrent/ re-entrant nature (RP); for example, a visual stimulus that is given sufficient time to evoke RP (i.e., is not masked within ∼50 ms) yet is not attended or is neglected, as in neglect, inattentional blindness , change blindness, or the attentional blink.

• Stage 4: Deep (or a better word may be “wide-spread”) RP. This is the case when RP spans the whole hierarchy from low level sensory to high level executive areas. This occurs when a stimulus is given sufficient time to engage in RP and is attended. Others have equated this to the situation that a stimulus has entered global workspace .

Or this description:

Initially, all objects are processed by low level areas in a feedforward fashion, so that basic features are extracted at about 100ms (Stage 1). Some objects are processed more deeply at about 200ms (Stage 2), depending on top down and bottom up attentional selection. Meanwhile, recurrent processing in early visual areas emerges also at about 200ms (Stage 3) for all or most of the objects. Later still, at about 300 msec, recurrent processing grows more widespread (Stage 4) for those objects that are selected by attention (potentially slightly different ones than those that were favored initially, as attentional selection is influenced by previous processing). After stimulus removal, Stage 3 processing turns into iconic memory, while Stage 4 processing turns into working memory.

It is difficult to envisage how what is significant could be decided and broadcast without the use of some structure like consciousness awareness in which it can be tagged. And it is hard to see how the brain could work without global priorities.

Besides the significance, there is an aspect of attention that is connected with language. E.B. Bolles (here) has been writing about this for a few years – and in his theory, the words in language steer attention so that the speaker and listener can mutually focus on the same topic. So if I start by saying ‘the car’ then my listener will focus attention on some object that fits that description and/or the concept of ‘car’ in the listener’s mind. This steering of attention may be a further reason (beside the need to use working memory) why language is almost always conscious. I will be returning to language again later.

There is more to come. Previous posts in this series:

Possible functions of consciousness 1 - leading edge of memory

Possible functions of consciousness 2 – gate to meaning

Possible functions of consciousness 3 – working memory

Possible functions of consciousness 4 – place to imagine

Possible functions of consciousness 5 – create ‘now’

Possible functions of consciousness 6 – presence ‘here’

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23/08/2011 by admin.

The phenomenon of ‘conflict adaptation’ is a cognitive control function that has been thought to only apply when conscious information is used, that is, information that can be held for some time in working memory. Conflict adaptation happens in priming experiments: when a prime corresponds to the target, the target is more quickly and accurately identified but the correspondence has affects not just in its own trial but the following one, so that an incongruent prime-target produces less priming effect in the next trial. Although the priming correspondence effect applies to both conscious and unconscious primes, the conflict adaptation appeared to apply only to conscious primes. Conflict adaptation is thought to occur because following a conflict (incongruent prime-target) pre-frontal cortex control processes increase control over perceptual processes in a top-down way.

In a recent paper (see citation below), the researchers found that if attention was not relaxed between trails, the conflict adaptation could occur with unconscious priming. They used the same experiment setup as Kunde in which the priming had to be conscious to get conflict adaptation. They made only two changes: they did not use a warning sound before a trial which forced the subject to maintain vigilance between trials; and, they shortened the gap between trials to less that 1.5 seconds from about 2-2.3 seconds. Under these conditions, unconscious priming also gave conflict adaptation.

These results add to the growing body of literature suggesting that unconscious information can influence high-level (prefrontal) cognitive control functions, such as inhibitory control, task switching, error correction and conflict adaptation (present study). These results further elucidate and expand the potential influence of unconscious information on our direct, but also future decisions.

van Gaal, S., Lamme, V., & Ridderinkhof, K. (2010). Unconsciously Triggered Conflict Adaptation PLoS ONE, 5 (7) DOI: 10.1371/journal.pone.0011508

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27/07/2011 by admin.

Binocular rivalry is an experimental setup where different images are projected to each eye. We do not consciously see both images but an alternative awareness of one and then the other. From paper sited below (Roeber, Veser, Schroger, O’Shea):

One sees one of the images for a few moments, referred to as the dominant image, while the other is completely invisible, suppressed. Then, after a brief period of transition, when both or parts of the two images are seen together, the other image becomes dominant and the first becomes suppressed. The images continue to alternate in visual consciousness randomly as long as one bothers to look at them. Binocular rivalry is an important phenomenon for researching the neural correlates of consciousness because visual consciousness changes without any change in the physical stimulation.

The cause of the rivalry have been proposed by two theories. It could be the top-down result of attention; or, it may be a bottom-up mechanism involving reciprocal inhibition and adaptation.

The behavioural, fMRI, and EEG evidence is consistent with attention’s being required for rivalry to occur. But Paffen et al. proposed an intriguing alternative hypothesis, at least for their behavioural results. They proposed that:

• Attention is not required for rivalry to occur,

• Attention increases the underlying neural activity of each of the representations of the rival stimuli that compete in the low-level rivalry mechanism; this is similar to increasing the contrast of the rival stimuli, and

• This increase in activity leads to greater adaptation, leading to faster alternations.

….We decided to test Paffen et al.’s explanation of attention’s effects on rivalry by measuring ERPs. ERPs are changes in electrical activity of the brain that follow some event, measured from electrodes placed on the scalp. ERPs have temporal resolution in the order of milliseconds. The typical form of the ERP when the event is the sudden appearance of a specific visual object or feature includes a positive component peaking about 100 ms after the event, the P1, and a negative component about 170 ms after the event, the N1. …If attention affects binocular rivalry by boosting neural responses to the rival stimuli, then attending to rival stimuli should increase ERPs from a change to a rival stimulus compared to when attention is on something else. If adaptation affects binocular rivalry and attention is accompanied by increasing adaptation, as proposed by Paffen et al., then attending to rival stimuli should decrease ERPs from a change to a rival stimulus. We found the latter: Attending to the rival stimuli decreases the size of the N1 compared with when attention is on something else.

In particular when attention was on the rival grating images and subjects had to report changes in the orientation the ERP (N1 160-210 ms) was smaller than when attention was on a fixation target distant from the grating images.

To explain this paradoxical effect of attention, we propose that rivalry occurs in the attend-to-fixation condition (we found an ERP signature of rivalry in the form of a sustained negativity from 210–300 ms) but that the mechanism processing the stimulus changes is more adapted in the attend-to-grating condition than in the attend-to-fixation condition. This is consistent with the theory that adaptation gives rise to changes of visual consciousness during binocular rivalry.

For my interest, this is a further separation of attention from consciousness. Although they are found together most of the time – they do appear to be separate processes.

Roeber, U., Veser, S., Schröger, E., & O’Shea, R. (2011). On the Role of Attention in Binocular Rivalry: Electrophysiological Evidence PLoS ONE, 6 (7) DOI: 10.1371/journal.pone.0022612

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