Are you paying attention?

“Millions of items of the outward order are present to my senses which never properly enter into my experience. Why? Because they have no interest for me. My experience is what I agree to attend to. Only those items which I notice shape my mind — without selective interest, experience is an utter chaos. Interest alone gives accent and emphasis, light and shade, background and foreground intelligible perspective, in a word. It varies in every creature, but without it the consciousness of every creature would be a gray chaotic indiscriminateness, impossible for us even to conceive.” 1,2

William James, The Principles of Psychology

How are you doing that, exactly? How does it feel?

Much like many other abstract concepts stemming from our inner life, it is something we can’t easily grasp, but rather intuitively define by contrast. It is far easier for us to pinpoint when someone is not paying attention, is distracted, or has lost track.

Merriam-Webster defines attention as “the act or state of applying the mind to something” or “a condition of readiness for such attention involving especially a selective narrowing or focusing of consciousness and receptivity”. 3

Simone Weil wrote that “Attention is the rarest and purest form of generosity”1, while cognitive scientist Alexandra Horowitz proposes a more pragmatic definition: “Attention is an intentional, unapologetic discriminator. It asks what is relevant right now, and gears us up to notice only that”. 1

Perhaps the best-known description of attention, however, comes from psychologist William James, who manages to address it with insight and empathy for the wandering human mind:

“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, localization, 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, scatter brained state which in French is called distraction, and Zerstreutheit in German.” 1,2

Is all attention the same?

Intuitive approaches aside, how do scientists define attention? A large number of studies measure and compare attention across subjects and even species. However, the exact nature of what is measured seemed so unanimously known, yet scarcely defined, that it prompted a 2011 review addressing just that: a taxonomy of attention. 4,5

In large, there are two main types of attention, depending on the kind of stimulus that triggers it:

  1. External attention – focusing on what is perceived from the outside world. This includes objects in the environment and their features, spatial locations, selecting relevant information from our senses as well as keeping track of time points.
  2. Internal attention – responsible for our inner thoughts, active during learning, defining an idea or remembering. This is the foundation for performing tasks, responding to stimuli, as well as passing information into working and long-term memory.

Another way to view this is that external attention is largely stimulus-driven, while internal attention is more goal-directed. However, this is not exclusive. An external stimulus can also serve one of our goals, which would further motivate us to pay attention.

Yet another approach to describe how we guide our attention divides it into bottom-up (an external stimulus that makes us pay attention to it simply because of its distinctive properties) and top-down (willfully directing our attention to a stimulus based on prior knowledge and goals).6

What can attention ‘do’?

Holds a few things at a time.

One particular characteristic of attention resides in its limit. In theory, attentional mechanisms evolved precisely so that we can direct our relatively limited processing capacity on the most relevant data at hand.

First off, a piece of information must wait its turn to be processed appropriately. You may find this when you try to perform two different tasks shortly one after the other. It appears that the shorter the interval between the two stimuli that need to be processed, the longer your response time in the second task will be. This latency, part of the Psychological Refractory Period phenomenon, is what led scientists to believe that people can only perform central processing of one particular task at a time.

This “central bottleneck“ is what makes multi-tasking so tricky. According to this theory, multi-tasking is not so much based on simultaneous processing of information, but rather rapid permanent switching between the different tasks at hand.

Experience the Psychological Refractory Period phenomenon for yourself in this psychological experiment.

Or try your hand at multi-tasking here.

Another consequence of the constrained nature of attention is that it creates competition. Sometimes, this can turn into confusion if multiple conflicting notions are presented simultaneously.

See for yourself in this classical psychological test, which assesses your ability to state the color of a word correctly. Sounds like an easy task, when in reality, your automatic processing of the meaning behind the word will often prove confusing.


A key aspect behind attention in the mind of many researchers is the now unanimously accepted fact that selection mechanisms must be at play throughout our everyday life.

This is to say that we come into contact with vast amounts of data just in the first 20 minutes after waking up – the amount of light, every object around the room, the sound of the alarm, the infinite notifications on our smartphones, everything that enters our visual field before we reach the kitchen, all the minute steps required to brew coffee, not to mention every inner sensation we experience in between. Processing everything equally would be exhausting, not to mention inefficient. Selection mechanisms help us choose what requires our focus and what can be run in the background.

Many questions persist: When does selection occur? After we perceive a stimulus? Before? Does some minimal processing take place in order to determine its importance? What happens with unselected information?

This feature of attention brings a remarkable level of efficiency to information processing, but it does have its shortcomings, as proven by the famous experiment of Simons and Chabris in 1999. 9

You can take part in the experiment as well, by just watching the short video below. Pay close attention.

So, did you see the gorilla?

The original experiment in 1999 reported that 46% of subjects did not notice the unexpected event, being prone to what came to be known as inattentional blindness. Whether it is a traffic light we miss because we were on the phone, an acquaintance we pass on the street because we are focused on our destination or, indeed, a gorilla, this phenomenon goes to show just how many things may take place outside our focus unless we willingly expand it.


Once an item is selected out of the multitude of stimuli that compete for our attention, its path towards the cortex can further be altered by the particular state of our focus. How fast we need to perceive something, how much precision a reaction to it requires, will we pass this into memory – all these are, at least in part, influenced by the attention we invest.

Vigilance allows us to sustain attention for an extended period of time, raising our perceptual and cognitive mechanisms to their peak levels. Think of the difference in your state of mind during an exam, or working on a specific project, versus relaxing in front of a TV show on a not-so-eventful Sunday afternoon.

Where does attention take form in the brain?

Although conclusive research to define which particular networks create attention is still underway, it is acknowledged what an important role the parietal lobe plays. So much so, that patients with significant strokes, especially to the right parietal lobe, may come to experience the hemineglect syndrome. These patients will start neglecting objects on their left side, although their sensory and motor functions may be intact. They stumble into objects, fail to draw the left side of any object, and even seem unable to recall features of the left side of a space. Interestingly, if asked to change the viewpoint in relation to the same space, they can remember it entirely, suggesting that there is no deficit in the stored memory, but instead in the act of recalling it.7

Current models propose that bottom-up directed attention is differently processed from top-down attention. A 2002 review suggests that segregated networks are required to carry out different attentional functions. One such system includes the dorsal parietal and frontal cortices and is responsible for top-down attention guidance. Another, including the temporoparietal and inferior frontal cortex, seems to be specifically designed to detect behaviorally relevant stimuli. It is supposed to act as a ‘circuit breaker’ for the first system, deflecting our attention to a particularly salient stimulus.8

A more recent review claims that attention affects the neuronal firing rate, as well as its variability and correlation across neurons in distinctive brain areas for bottom-up and top-down attention. Nevertheless, it finds that the frontoparietal network serves as a common structure, essential in both types of attentional processing. 6

Bottom-up attention is then described as a path that begins with a basic visual perception, that reaches the primary visual cortex, then traverses various cortical areas and branches, giving rise to a ventral pathway (dealing with objects and their features) and a dorsal pathway (responsible for space and movement processing).6

As far as top-down attention goes, current theories suggest that signals which pre-determine what kind of stimuli we should focus on originate in higher cortical areas, such as the prefrontal cortex or the posterior parietal cortex, and end up acting on the visual cortical areas, with the same ventral and dorsal pathways. Recent research focuses increasingly on the interplay between bottom-up and top-down modulation, seeing how they seem to converge in certain cortical areas and involve similar mechanisms.6

Attention, this capacity to select most relevant stimuli from the world, despite the incredible amounts of data we are presented with, is an intricate matter which, for good reason, continues to fascinate psychologists and neuroscientists alike. Even more so in the context of our modern fast-paced, informationally suffocating world, where quick filtering is vital. More on that in a future article.


  1. William James on Attention, Multitasking, and the Habit of Mind That Sets Geniuses Apart – Brain Pickings. Available at: link. (Accessed: 24th June 2020)
  2. Classics in the History of Psychology -- James (1890) Chapter 11. Available at: link. (Accessed: 25th June 2020)
  3. Attention | Definition of Attention by Merriam-Webster. Available at: link. (Accessed: 24th June 2020)
  4. Chun, M. M., Golomb, J. D. & Turk-Browne, N. B. A Taxonomy of External and Internal Attention. Annu. Rev. Psychol. 62, 73–101 (2011)
  5. A taxonomy of attention – Irene Vigué-Guix. Available at: link. (Accessed: 25th June 2020)
  6. Katsuki, F. & Constantinidis, C. Bottom-up and top-down attention: different processes and overlapping neural systems. Neuroscientist 20, 509–21 (2014)
  7. Husain, M. Hemineglect. Scholarpedia 3, 3681 (2008)
  8. Corbetta, M. & Shulman, G. L. Control of goal-directed and stimulus-driven attention in the brain. Nat. Rev. Neurosci. 3, 201–215 (2002)
  9. Simons, D. J. & Chabris, C. F. Gorillas in our midst: Sustained inattentional blindness for dynamic events. Perception 28, 1059–1074 (1999)