Can People Multitask?
People can’t multitask effectively. Giving simultaneous attention to tasks, or alternating and dividing attention between tasks, reduces the performance of at least one task. This is true in almost all cases, however, some select people suffer less performance loss when multitasking. Also, certain types of information pair better together for multitasking due to the way our memories work. 
In truth, most people can’t actually focus on more than one thing at once. Our hardwiring is designed to quickly switch between tasks (divided attention) rather than focusing on more than one thing at the same time (simultaneous attention).
Below we look at multitasking, the different types of attention, the way our brain evolved to handle our attention, our limited short-term working memory, and the way memory and attention work together.
Why Can’t People Multitask Effectively?
In simple terms, we can’t multitask because our attention and short term memory aren’t wired for splitting attention as a matter of efficiency. If we had more adapt attention skills we would face information overload due to the way our memories work (this is explained in detail below). This means that even an above average person will still struggle with attention and memory.
Our short-term working memory has a limited capacity, it can only hold about 5 – 7 pieces of information at once. Attention is needed to grab the stimuli we perceive with our senses, turn those into short-term memories, and turn those short-term memories into long-term ones. It would not be efficient to let more data in than we do, we have a really crazily big storage capacity, but other factors (like the way we organize information) require us to moderate our sensory information intake.
A video talking about why humans can’t actually multi-task effectively.
What is Multitasking?
Multitasking roughly means doing two things at once, specifically multitasking is the alternating and dividing of attention, it is not focusing on more than one thing at once (as commonly assumed), that is called simultaneous attention. Below we look at how the different types of attention are functionally and biologically different.
FACT: A U.S. study showed that simultaneous attention was more likely to occur in children with an indigenous background than those with European-descent (who were wired to practice divided attention).
Different Types of Attention
The different types of attention can be defined as (tip this is theory based):
- Focused Attention: The ability to focus on a particular thing.
- Sustained Attention: A sustained focused attention on one thing.
- Selective Attention: The ability to filter out distractions and give priority to tasks.
- Alternating Attention: Ability to switch back and forth between tasks that have different cognitive requirements.
- Divided Attention: Dividing attention between multiple tasks at once, “splitting attention”. This one can be confusing as humans can’t actually focus on more than one thing with full attention. What we think of as dividing attention is essentially alternating attention quickly. Alternating and prioritizing attention typically comes at the cost of reduced performance of at least one of the tasks.
- Simultaneous Attention: Simultaneous attention is the concept of simultaneously dividing attention between multiple tasks, without alternating attention. This is rare and is only shown to occur in specific cases. For instance, continuous partial attention (CPA) is where someone pays attention to only basic details (attempting to take an equal loss on all tasks rather than just one task).
NOTE: Our understanding of attention used to be somewhat theoretical, but recent advances in neurosciences have begun to paint a clearer picture of what is happening in the brain. It turns out we simply aren’t hardwired to pay attention to more than one thing effectively.
Parts of the Brain that Deal With Attention
Different parts of the brain control the different attention types we used in the model above. They are:
- The Parietal Lobe: deals with orienting attention. This includes:
- Overt orienting selectively shifts focus by moving the eyes to an object.
- Covert orienting mentally shifts focus.
- Exogenous orienting (bottom-up attention) orients attention as a reflex to stimuli.
- The Prefrontal cortex: orients attention to goals and desires. The part of the brain that deals with complex cognitive behavior, decision-making, personality, and goals.
- Endogenous (top-down attention): Decision making.
- Endogenous (top-down attention): Decision-making. Orienting attention to goals and desires.
- The Frontal Lobe: Which deals with maintaining our attention.
- The Anterior Cingulate: Which deals with controlling or regulating our attention.
NOTE: Some types of attention use more than one part of the brain. For instance maintaining attention also uses the frontal lobe.
A video talking about how our brains work in regards to attention.
Why Can’t People Focus on More Than One Thing Effectively?
When one splits attention (“time-sharing” attention), one or more tasks tend to suffer from performance loss. It’s helpful to think of attention like a spotlight, it can only shine on one thing at a time. We can pop back and forth between a few things, but typically it’s at the expense of another. Attention takes effort and brainpower and that is a limited resource.
The ability to multitask effectively is impacted by a number of factors including genetics, how a given person’s brain works, training, the difficulty of the given tasks, and what parts of memory a task is using.
Learning to divide attention between alternating focuses effectively is probably the closest thing to “being good at multitasking” as one can get. Certainly some are better at this than others for reasons of both nature and nurture.
Change Blindness and Attention
One of the things that help prove the limitations of attention and memory, aside from the studies, is something called “change blindness”.
Change blindness is any change a human fails to notice. Given our natural tendency to focus attention as a spotlight and the natural hard-wiring of our brains, we tend not to notice changes in our environment that our brains deem “not useful.” This is a matter of the brain being efficient. It is not evolutionary necessary for us to notice subtle changes.
For example: In the video below about half of the people don’t realize that the first person they talked to is different from the second. The brain doesn’t expect a person to change, so we aren’t hardwired to pick up on this change. In other words, we aren’t trained to pay attention to certain types of changes. If we don’t pay attention to something, we don’t notice it and it never makes it to our memory.
We can understand change blindness a little better by looking at the concepts of “fast thinking” and “slow thinking”
A video about change blindness from NOVA.
FACT: Illusionists who use this loophole to perform slight of hand magic and other tricks exploit knowledge of change blindness. The limitations of attention and memory are at the root of a lot of illusion, magic, and mentalism tricks.
Fast Thinking Versus Slow Thinking
- Fast Thinking: Fast, automatic, frequent, emotional, stereotypic, subconscious
- Slow Thinking: Slow, effortful, infrequent, logical, calculating, conscious
Think fast, it’s a video about fast thinking.
In regards to attention, slow thinking requires our attention to be focused on it while fast thinking is automatic and requires no conscious attention. This can result in us not noticing changes unless we are consciously applying slow thinking and attention to things our brain would process subconsciously. This goes hand-in-hand with change blindness, our inability to multitask, and something called “working memory”.
How Does Attention Affect Memory?
Attention and memory work together to turn outside stimuli into experiences and memories. When your brain senses something a memory is briefly held in “sensory memory”. You can then direct your attention (consciously or subconsciously) at any sensory memory and it then moves into working memory. How working memories are processed has a lot to do with how our attention is focused and that then, in turn, dictates what long-term memories will be stored.
The problem is, both attention and working memory storage are fairly limited resources.
Fig 1. The Working Memory Model (Baddeley and Hitch, 1974). Source.
Miller’s Law and Working Memory
Some think that miller’s law overestimates our ability to store short-term information storing as little as 2 to 4 memory blips at once. As you can imagine, this doesn’t bode well for our ability to effectively multitask.
Clarification on the amount of pieces of information we can store in memory: The number of pieces of information a person can hold in short-term working memory is debated. Think about playing a game of telephone (where each person has to remember the items of the last). The average lengths of lists in games of telephone would align pretty well with the amount of different pieces of information that can be stored in short-term (not long-term) working memory.
FACT: Telephone numbers being 7 digits long are based on the idea that the average person can hold about 7 pieces of information in their head at once.
Humans have three types of working memory (meaning they can be accessed and worked with): short-term working memory, long-term working memory, and intermediate-term working memory.
Long-term and Intermediate-term
Long-term memory is fairly theoretical and is used to account for working memory drawn from our long-term memory, but repetition and REM sleep seem to play significant roles is cementing things in long-term memory.
Short-term working memory (or just working memory) is more relevant to multitasking because of the demands on one’s attention.
Short-term working memory
Our long-term memory can hold a lot of information, but our conscious short-term memory space is very limited. Learning, reasoning, and comprehension all require short-term memory and short-term memory requires attention.
We get about 5 – 7 pieces we can remember at a time and each stays in our short-term memory for about 20 seconds before being committed to long-term or discarded. We must use our attention to decide which blips of working memory are important and which aren’t.
The “Use it or Lose it” Rule
When our brain deems something in short-term memory important it commits it to long-term memory. However, due to synaptic plasticity we only truly store stuff in a meaningful way when it is useful and therefore used.
In other words, long-term memory has somewhat of a “use it or lose it rule”. Again our attention comes into play as our attention can draw memories out of long-term memory as easily as it can help us pick up on sensory memories, direct them to working memory, or direct working memories to long-term memory.
FACT: This is why cramming for a test is next to useless. You can store lots of information, but if you don’t use it or connect it in a meaningful way you can lose it. Long term memory lasts anywhere from a few hours to a lifetime.
Types of Information That Can Be Stored in Memory (Sensual Memory)
There are a few different types of information that can be stored in memory those can be categorized as spatial and non-spatial. This generally includes spatial, visual, and auditory, but other stimuli like smells, touch, and more can also be remembered.
In humans, spatial memory is the part of memory that records information about one’s environment and its spatial orientation. Visual memory records information about the way things look. Auditory memory records information about sounds. Likewise other memory would be information recorded based on the sense like touch or smell.
Before memories even get to short-term memory they must first be processed as sensual memory. The image below gives a good visual representation of how things go from stimuli to sensory memory, to attention, to working memory, to long-term. You can learn more about how memory works here.
Different Types of Tasks Perform Better Together
Given the different memory types and the limited short-term storage capacity, we can conclude different types of tasks play better together for attention splitting. For instance, it’s generally easier to “multitask” between tasks that require different information types and different degrees of attention (for example it’s easier to do one visual task and one audio based task, then it is to focus attention on two tasks that use the same part of our memory.)
The image below shows one of the most widely accepted models for how the brain separates processing visual / spatial information from audio information.
Implicit and Explicit Long-Term Memory
For one, we can use implicit and explicit long-term memory to the mix. Explicit memory is stored long-term memory that requires conscious thought and implicit memory is a long-term memory that doesn’t require thought. We can utilize these to multitask better as they aren’t necessarily taking the same short-term storage as short-term memory.
An example would be a trained musician performing with others. They may be splitting attention between the other players, the music, their instrument, the song, and more, but because so much of this has been committed to long-term memory through training they can more effectively work their brain to execute their performance.
Can People Improve Their Attention?
The good news is that attention can be improved. You can practice cognitive skills that improve your focus and attention. Most will require an active participation in re-wiring your brain to be more effective at multitasking or even simultaneous attention. The lack of focus isn’t an inherent human trait as much as it is an evolutionary one (judging by the attention types and the study that showed indigenous people better suited for simultaneous attention).