Attention is a broad term that many people have a basic understanding of, but I want to review the definition, levels of attention, and real life examples of each level in action. 

Definition of attention: 

Attention is the ability to choose and concentrate on relevant stimuli and is an absolutely foundational cognitive process.

Levels of attention: 

Research studies have proposed theories of attention levels or types. A common theory developed by Sohlberg & Mateer is that there are five different domains of attention organized into a hierarchy: focused, sustained, selective, alternating, and divided attention. Each of us utilizes these types of attention many times per day, sometimes simultaneously. The idea behind this hierarchy is that each level of attention requires varying levels of mental effort or energy. In general, as you move up the hierarchy, the amount of mental effort required increases (and often the complexity of the task). Each domain below in the hierarchy is foundational to the domain above it. Adults with acquired brain injuries or neurological disorders may have attention challenges with all five levels or just some of the levels depending on the person. The chart below taken from the Mild TBI Rehabilitation Toolkit is a helpful visual:

Examples of each level:

1. Focused attention- You are walking through the produce section at the grocery store and locate an item (spinach) that you were looking for on your list. 
2. Sustained attention- You sit down to read a novel for 30 minutes.
3. Selective attention- You cook dinner in the kitchen while your kids are playing/talking in the adjacent room.  
4. Alternating attention- You are working on a Powerpoint presentation at work when a coworker comes over to your desk, asks you a question about an unrelated topic, then you return to your original task of working on the Powerpoint. 
5. Divided attention- You are driving/navigating in the car while simultaneously having a conversation with your friend. 

One final note about attention: personal and situational factors impact a person’s attention significantly, so it is crucial to mitigate these factors to really optimize the ability to pay attention. If you just had an argument with your significant other, if you are in a particularly overstimulating environment, if you have a headache, or if you didn’t sleep well last night- these are all examples of when it becomes even harder to pay attention. This is true for everyone, regardless of whether or not you have had a brain or neurological injury, but it’s even more critical for those who have increased challenges with attention as these external factors typically come into play more often.

Sources: 

Mild Traumatic Brain Injury Rehabilitation Toolkit by Weightman, Radomski, Mashima, & Roth