The human brain has a number of remarkable qualities, one of which is its ability to do many things at once. Parallel processing allows multiple streams of information to be processed by various parts of the brain simultaneously. Here, we explore what parallel processing is, how it works in the brain, and why it can matter for mental health. 

What is parallel processing in psychology?

The human mind can do multiple things at once; parallel processing is the mechanism behind this. It is the process by which the brain can carry out two or more operations simultaneously, processing each independently.

Core definition and basic idea behind parallel processing

A fundamental part of parallel processing is that it helps the brain identify and process several pieces of information at once rather than working through them one at a time. One way to think about it can be to imagine the brain as a highway rather than a single-lane road. Multiple processes run alongside one another, largely without us being aware that they’re happening.

How parallel processing fits into cognitive psychology

As mentioned, the theory of parallel processing suggests that the brain processes multiple pieces of information at the same time. This idea was first developed in the 1980s as an alternative to previous theories of information processing, which suggested that the brain processed information sequentially, that is, by processing one thing at a time. Cognitive psychology applies this framework to explain various processes, including memory and decision-making.

How parallel processing works in the brain

To understand how parallel processing works, it can help to understand just how much is going on inside the brain.

Processing incoming stimuli at the same time

Different components of the brain working together

Parallel processing works because different components of the brain are each responsible for different types of information. For example: 

• Cerebellum: Containing more than half of the neurons in the adult human brain, the cerebellum can support fast, effective, and ever-changing sequences that are required to perform tasks relatively automatically.
• Cerebral cortex: Also known as gray matter, the cerebral cortex is connected to the cerebellum with a complex system of channels. Experts believe the cerebellum uses these channels to distribute information for processing.
• Thalamus: The thalamus acts as an interface between the periphery and the cortex, relaying sensory information for fast processing.
• Amygdala: The amygdala quickly processes the emotional significance of stimuli to support rapid decision making.

Parallel processing models and theories

Researchers have developed various models to explain how parallel processing may operate, models that attempt to understand the architecture that allows the brain to think in multiple directions at once.

Parallel distributed processing models

Parallel distributed processing models propose that, rather than being a fixed set of data, information is processed through an essential network of scaffolding, and that these networks of interconnected units each contribute a small part to the development of a whole.

According to these parallel models, information is distributed across many elements of the network at once rather than being stored in a single location. Because of this, the same data can be used in many different processes simultaneously, adding efficiency and flexibility, which can help account for the brain’s ability to process information.

Parallel processing vs sequential processing

Not all mental processing happens at once. Sequential processing is a different approach that involves working through information one step at a time in a fixed order. Understanding the contrast between parallel and sequential processing can reveal much about the mind's possibilities and limits.

Sequential and serial processing explained

Sequential or serial processing is a method in which the brain handles tasks in a strict, ordered sequence. Rather than spreading information across a network, serial processing moves one step at a time, progressing only when the previous step is complete. Sequential processing requires careful attention and effort. It’s slower and more deliberate, which is why it is more effective than parallel processing for tasks that require multi-step instructions, complex decision-making, or learning something new.

Key contrasts and serial bottlenecks

The contrast between sequential and parallel processing can become more apparent when performing under pressure. Parallel processing generally handles automatic functions and routines with ease, while sequential processing has limits. 

For example, one well-documented limit to sequential processing is a serial bottleneck, the point at which the brain can only manage one demanding task at a time, which causes a delay when another demanding task arrives. This bottleneck can explain why it may not be possible to multitask on two complex activities. Instead, it may be more likely that the brain rapidly switches back and forth between the two activities as their complexity means they are competing for the same resources.

Bottom-up processing and perception

Bottom-up processing is how the brain takes in raw sensory input, independent of previous knowledge or experience. In other words, it’s how the brain takes data from the senses and builds meaning and understanding.

How sensory input is processed in parallel

Bottom-up processing begins when sensory input enters the system, such as sound reaching the ears, wind blowing against the skin, or light entering the eyes. Rather than processing one type of input at a time, multiple streams are processed simultaneously, sending information to various parts of the brain. This is why our perception of the world around us can feel seamless and easy, even though there is a lot of processing going on underneath the surface.

Depth, form, motion, and object recognition

A good example of how bottom-up processing works is visual perception. Parallel processing allows the brain to process several characteristics of a scene at the same time. While the brain regions that process form, color, and motion vary, these regions work concurrently. The brain simultaneously recognizes the shape of an object while determining whether it is moving and how far away it is. This process contributes to why we can step around an obstacle while walking, recognize friends’ faces in large groups, or catch a ball thrown to us.

Examples of parallel processing in everyday life

Parallel processing can seem abstract, but it occurs in our brains all the time, even during the most ordinary moments in various aspects of life. 

Performing tasks simultaneously

Parallel processing is automatic and doesn’t require any effort, but it is something your brain is doing all the time. Some examples include: 

• Having a conversation while walking
• Listening to music while driving
• Driving a familiar route while thinking through a problem
• Walking on a treadmill while watching a TV show

Real-world and behavioral examples

Beyond everyday multitasking, parallel processing can give us the ability to do a number of activities that can be easy to identify once you know what to look for. The following examples demonstrate that multiple complex processes can be represented in various real-world examples, running in parallel while contributing to a single outcome.

• A goalie tracking the ball across a field during soccer practice, calculating the speed, distance, and trajectory while physically positioning themselves to stop the goal
• A chef cooking multiple dishes at various stages of preparation at once, while coordinating with kitchen staff to serve customers quickly and accurately
• A surgeon operating on a patient, using their hands to perform intricate work while monitoring vitals and working with other members of the surgical team.

Getting support through BetterHelp

Psychology has shown us that the mind is complex, processing our environment in ways that we are not consciously aware of. Recognizing that our emotional responses, thought patterns, significant relationships, and behaviors can be the product of automatic processes can help us better understand our mental health. Working with an online therapist can help you better understand these patterns and strengthen your ability to recognize thoughts and behaviors and respond to them with greater intention.

Therapy tools that help people manage complex information

Therapists can use a variety of approaches to help clients engage with and understand the complexity of their thoughts and behaviors. For example, cognitive-behavioral therapy focuses on identifying unhelpful thoughts and behaviors and learning how to reshape them over time. If you are facing challenges in your life, a BetterHelp therapist can meet you where you are, offering practical, personalized support.

Online therapy has been shown to be an effective, viable alternative to in-person therapy for a range of conditions. For example, evidence in one study comparing online and in-person CBT shows that online CBT was “a flexible, accessible, and empowering alternative to traditional in-person therapy.”