Perception

Definition of Perception

Many objects around us would have no meaning if our brains did not organize information coming from them. This process of organization is called perception.

Bottom-Up vs Top-Down Processing

When perceiving objects around us, our brain engages in two types of processing - bottom-up and top-down. For example, as soon as we see the letter 'P', our brain's perception immediately identifies it as that letter. No additional processing is required as the brain already has the information to recognize the letter from the visual information it is receiving. This is called bottom-up processing.

Bottom-up processing during perception is often driven by data and usually occurs in real-time. Other times, the brain needs to use a higher level of mental processing to understand sensory information. This type of processing is called top-down processing.

In top-down processing, the brain uses contextual clues to understand unknown sensory information. Take the following image, for example. We can read the middle square either as "13" or "B". This depends on our perception as we read top-to-bottom or left-to-right.

Fg, 1 Squares with numbers and letters. StudySmarter Orginal

How Do We Perceive the World?

There are four types of perception: energetics, mind, matter, and the heart. All of them are based on certain principles and cues.

Gestalt Principles of Perceptual Organization

Gestalt psychology is a school of thought that proposed that the brain perceives the whole before perceiving the many parts of the whole. It was established in 1912 by Max Wertheimer. Gestalt psychologists have compiled an extensive list of Gestalt psychology perception principles. Some of those are:

• Similarity (perception groups together similar objects).

• Proximity (perception groups together objects proximally close to one another).

• Continuity (perception continuous line rather than smaller, disjunct pieces).

• Closure (perception completes missing information to form a whole).

Depth Perception

How can we see that a box is square or that a car is racing toward us? Our brain's ability to perceive depth allows us to see beyond the two-dimensional images we receive from each eye. This ability is called depth perception.

Without depth perception, it would be challenging to judge distance. Our brain uses visual cues from one or both eyes to process an object's depth perception or distance.

Monocular Cues

Monocular perception cues refer to the three-dimensional processing the brain completes with only one eye.

Monocular perception cues can include the following:

• Relative height (objects that appear smaller and higher up are farther away).
• Interposition (overlapping objects tells us which is farther).
• Linear perspective (parallel lines converge further away).
• Texture gradient (the texture of a surface becomes blurry at further distances).
• Light and shadow (lighter objects that appear closer).

Fg. 2 Tree alley, pixabay

Binocular Cues

Our eyes have two different perspectives of the world. Therefore, some depth perception cues can only be perceived through both eyes.

The information that the brain receives from both eyes enables us to judge distance by comparing the images from both eyes. This process is called retinal disparity. Binocular perception cues also allow us to have perceptual constancy. For example, if a car is moving towards you, the image of the car gets bigger. However, your perception is that the car is not growing in size but is simply getting closer.

Selective Perception

Our brains are selective about what we pay attention to (selective attention) and what we don’t pay attention to (selective inattention) during perception.

Selective Attention

We receive an overwhelming amount of sensory information at every moment, influencing our perception. The brain is limited in the amount of information it can attend to at a single moment. Therefore, we must pick and choose where we place our attention.

Have you ever been to a loud party but were still able to catch up with an old friend? Selective attention allows you to focus on the perception of your conversation while also drowning out the other voices in the room. This is often referred to as the cocktail party effect. If our brains were unable to participate in selective attention, these situations would be far too overwhelming, making it impossible for us to focus enough to hold a conversation in this scenario.

Contrary to popular belief, the brain can only focus on one task at a time. Multi-tasking is a myth. If a stimulus is salient and unexpected, attention can easily be pulled away. This is exactly why texting while driving is proven to be extremely dangerous. A person cannot focus entirely on driving while simultaneously replying to a text.

In a study done by Brasel and Gips (2011), researchers placed subjects in a room for 28 minutes with television and internet access. They observed that the subjects switched their attention 120 times on average.

Selective Inattention

On the other side of the coin, selective inattention is when the brain might fail to pay attention to certain stimuli while our focus is directed elsewhere. One example is inattentional blindness.

Many studies have tested this phenomenon. Simons and Chabris (1999) conducted an experiment in which viewers were asked to count the number of passes completed by a group of people. In the video, someone dressed in a gorilla suit walks into the frame for a few seconds, beats their chest, and walks out. It was found that half of the participants did not even notice the gorilla. The viewers were too focused on the task at hand to count the number of passes, and their brains did not perceive the distracting stimulus that appeared on the screen.

Is it True That "Perception is Reality"?

Through top-down processing, perception is our brain's reality. Gestalt psychology perception principles identify how the brain perceives the whole before perceiving the basic components of sensory information. Additionally, our previous experiences play a large role in our perception of a specific stimulus.

Perceptual Set

Gestalt psychology perception principles are a group of laws that are generally true for most people. However, there are situations in which our perception differs from one another due to a predisposition. This is called a perceptual set.

Our previous experiences can significantly influence our perceptual set. It's what tells us what to expect and steers our perception in similar situations. Certain associations can be activated through a process called priming, during which we form our predispositions of perception. The concepts, or schemas, we form are used to organize the information we receive. Schemas can take the form of stereotypes or social roles.

Other possible influences on your perceptual set include context, motivation, or the emotion we may be experiencing in a moment.

Self-Perception

How we view ourselves, or our self-perception, can be influenced by what we see and experience externally. However, sometimes it can go the other direction, and our self-perception can affect how we view the world around us. For example, a person's self-perception can influence what they see in the mirror. A person could have a small scar on their face, but their perception is that it is much bigger than it is. This can depend on one's self-perception. Self-perceptions are subjective perceptions and can play a significant role in forming attitudes towards body image (Cash, 2012).

Fg. 3 Positive self-perception, freepik