Sensation

Sensory receptors in our sense organs respond to information in the world and send this to the brain, a process called sensation. For example, light causes changes in eye cells which relay messages to the nervous system. We call this information stimuli.

You probably know about our five major senses, but were you aware we also have systems that provide information about balance, body position, movement, pain, and temperature?

Our sensory systems:

• Vision
• Hearing (audition)
• Smell (olfaction)
• Taste (gustation)
• Touch (somatosensation)
• Other senses: Balance (vestibular sense), body position (proprioception), body movement (kinesthesia), pain (nociception), and temperature (thermoception)

Perception

Our sensory receptors are constantly collecting information from the environment. However, our interactions with the world are affected by how we perceive that information. Perception is how we interpret sensory information either automatically (bottom-up) or based in knowledge (top-down)^[6]. For example, imagine searching for keys: you focus on a yellow key chain in sensible places. This is top-down processing influenced by knowledge and expectancy.

Now imagine sitting in a crowded restaurant eating lunch and talking with others. Suddenly, there is a loud sound of breaking glass and clang of metal pans hitting the floor. That crashing sound would likely grab our attention – our brain would have no choice but to notice the sound and then interpret it. Because this attentional capture was caused by the sound from the environment: it would be considered a bottom-up process.

Sensation vs perception

One way to think of the difference between sensation and perception is to remember that sensation is a physical process, whereas perception is psychological. For example, imagine walking into a kitchen and smelling the scent of baking cinnamon rolls, the sensation is the smell receptors reacting to the odor of cinnamon and sending information to the brain, but the perception might be “Mmm, this smells like the holiday bread that Grandma used to bake when I was a kid”.

Sensation is physical; perception is psychological. Smelling cinnamon is a sensation; recalling holiday bread is perception.

Although sensation and perception are defined as separate processes, they are almost impossible to separate, since each influences the other. For example, the strength of a sensation changes with sensory adaptation: If you burn a cake, you might stop noticing the smell after a while, but your roommate will smell it right away.

Similarly, attention affects what we sense and perceive. In a noisy environment, we can tune out background noise to focus on a conversation (top-down processing). Attention determines what we notice in our environment.

The Influence of Culture and Experience

Cultural psychologists, like Shinoba Kitayama and Richard Nisbett and their colleagues, have conducted multiple studies on the effects of culture on visual perception.^[1] In general, White people from the USA tend to be more individualistic in their outlook, whereas people from East Asia are more collectivistic and place a greater emphasis on the importance of community. Multiple studies have shown that US participants tend to focus on central elements in a picture or scene—like the globe in Figure 5.3, whereas East Asian participants attend more to context. Therefore, East Asian participants are more likely to notice the background objects as well as the larger objects in the foreground.^[2]

Culture can also affect our susceptibility to visual illusions. Marshall and colleagues found that individuals from industrialized cultures were more prone to experience certain types of visual illusions than individuals from non-industrialized cultures^[3]

These cultural differences in perception are consistent with differences in the types of environment that people experience. For example, people who are used to seeing buildings with straight lines, often referred to as a “carpentered” world^[4] are more susceptible to the
Müller-Lyer illusion (Figure 5.5) than people living in non-industrialized countries. The Zulu people of South Africa, whose villages are made up of round huts arranged in circles, are less susceptible to the illusion.^[5]

The cross-race effect is another example of how visual perception is affected by culture and experience. We are better at recognizing faces of people of our own race than we are at recognizing those from other races.^[6] In one study, Lee and Penrod found that participant race determines the extent of the cross-race effect. They found that, Asian, White, and Latinx participants all showed larger cross-race effects for Black faces compared to faces of other races.^[7] In other words, people who are not Black have more difficulty recognizing Black faces than White, Asian or Latinx faces. Poorer recognition of Black faces has widespread societal implications, ranging from hurtful classroom interactions where Black students are mistaken for other students^[8] to the increased rates of misidentification of Black people by people witnessing crimes and misdemeanors.^[9] However, research by McKone et al. (2019) offers hope for addressing these issues. They found that exposure to faces of different races before the age of 12 years can help mitigate the cross-race effect.^[10] This suggests that by promoting diverse environments from a young age, we can work towards a future where less discrimination occurs.

Other Factors That Affect Perception

Many other factors can influence perception. Have you ever been expecting a really important phone call and you keep thinking that you hear the phone ringing, only to discover that it is not? If so, then you have experienced how motivation can shift our ability to discriminate between a true sensory stimulus and background noise. Signal detection theory explains this – our ability to detect a stimulus depends on its physical properties and also on the psychological state of the observer. This might explain why a mother is awakened by a quiet murmur from her baby but not by other sounds that occur while she is asleep. Signal detection theory has practical applications, such as air traffic controller accuracy. Controllers need to be able to detect planes among many signals that appear on the radar screen and follow those planes as they move through the sky.^[11]

Another influence on perception ispersonality. For example, children described as thrill seekers are more likely to show taste preferences for intense sour flavors than children who are not.^[12] Expectations influence perception, as demonstrated by consumer research on brands and packaging. For example, in a taste test, participants who identified as Coke drinkers preferred Pepsi when it was served from a Coke bottle more than Coke served from a Pepsi bottle, and vice versa for Pepsi drinkers.^[13] An fMRI study showed that participants rated the same wine as tasting better if it had an expensive price tag compared to a cheap one.^[14] Also, popcorn tastes sweeter if served in a red bowl and saltier if served in a blue one.^[15]

On the next sections, we present three more ways to think about perception. First, a story about how psychologist study developing senses in infants. Second, an introduction to the concept of Theory of Mind, which is about taking the perspective of the other. Finally, we describe the concepts of Gestalt as it relates to sensation and perception. It all comes together to illustrate the theme of “Our perceptions and biases filter our world through an imperfect personal lens.”

Human Development

You might be wondering when and how our sensory systems develop in the first place, in order for perception to occur. It turns out that all of our senses are stimulated to some extent when we are still in the womb (prenatal), with the exception of vision.  All sensory systems need to be stimulated early in life in order for them to develop normally.^[16] The timeframe within which they need to be stimulated is called a critical period, and the exact timing of critical periods varies across our senses. Permanent deficits can arise if normal stimulation does not occur during a critical period.

When we are born, our visual system is less developed than our other sensory systems (since it is not stimulated prenatally. If a newborn has problems that prevent them from seeing normally in the first year of their life, they have permanent difficulties with perception of faces for the rest of their lives.^[17]It is important to detect and resolve any sensory issues, e.g., eye and ear problems as early as possible^[18]When you enter this world as an infant, you’re not wired full of memories that your brain will use to predict. Other people cultivate your world and as a consequence, they are wiring your brain full of experiences that your brain will then use to predict. You didn’t have a hand in creating that world, and you are not responsible for it.

Research Story: Garlic Babies

If you are now wondering how psychologists can study sensation in babies that haven’t even been born yet -you are asking good questions! Indeed, it’s a pretty big claim to say that we start learning even before we are born.

Developmental psychologists have developed methods of working with prenatal and just-born infants to get a peek into how, and even if, babies can learn before they’re born.

In a study by Hepper in 1995, he wanted to know if infants could recognize a smell of a food they were exposed to before they were born – in this case, garlic. Participants were twenty mothers and their infants who were assigned into one of two conditions; a garlic condition and a non-garlic condition. The condition they were in depended on a pre-study survey that asked about garlic preferences.

The ten mothers who were in the garlic condition ate fresh garlic in their meals at least three or four times a week for the last month of their pregnancy. The non-garlic condition was just that, where the mothers didn’t eat any meals containing garlic for the last month of their pregnancy. All twenty of the mothers had normal pregnancies and had healthy babies. Also, it is important to note that the newborns were bottle fed, so were not getting any garlic exposure through breast milk.

In order to make sure the learning was truly prenatal in nature, Hepper and his team tested the infants 15-28 hours after birth. The researchers smeared garlic paste on a piece of wool for the experimental stimuli as well as had a regular piece of wool for the neutral stimuli. They placed the pieces of wool on either side of the newborn, making sure the infant’s head started in a neutral place not looking at either piece of wool. They were looking to see if the babies would turn towards or away from garlic (helpful knowledge – looking time and direction is a valid way to get preference data from infants!). If the babies turned towards the garlic wool, then that would show a preference for the garlic smell. If the babies turned away from the garlic, then that would mean they had an aversion or did not like the smell.

What did they find? They found that the babies in the garlic group would turn their head towards the piece of wool that had the garlic paste on it, and statistically indicated a slight preference for garlic. However, the babies in the non-garlic condition showed a statistically significant aversion to the garlic smell and would turn away. The researchers want to conclude that the aversion to garlic in the non-garlic group and the slight preference for garlic in the garlic group demonstrate the infant’s ability for prenatal learning. It does seem likely that infants get olfactory input prior to birth.

There are many other studies about prenatal learning – and research shows that infants also can learn about stress and be predisposed to language and music if their prenatal environment provides those experiences. There is pretty strong empirical evidence that learning can happen before we are born.

Theory of Mind

Theory of mind (ToM) is a concept in psychology that basically means being able to consider other people’s mental states, such as desires, thoughts, and beliefs. Once you realize that everyone truly has a different perspective, you might want some practice in understanding that. Theory of mind isn’t an innate ability for humans, but rather one that is developed over time and experiences. This means that there are individualistic differences in ability and complexity of being able to ‘read’ other’s theory of mind. 

Development

Theory of Mind is often studied through a developmental lens. One common way to access children’s theory of mind is through a task called the False Belief task, also called the false location or Sally-Anne task. This task involved children watching a character – let’s call them Sally-Anne – place an object in one location, then character B – let’s call him Max – comes and moves the object to a different location when character Sally-Anne leaves. When character Sally-Anne comes back, they are asked where they will look for the object – in other words, where does Sally-Anne think the object is?

A child who has developed theory of mind can take the perspective of Sally-Anne, and reasonably assume they would look where Sally-Anne had left the object and not where Max had moved it to, because Sally-Anne didn’t observe the object moving. However, children who have not yet developed ToM will think Sally-Anne would look where the object had been moved to, because the child had seen it move. Children aged 3-4 failed this false belief task, children aged 4-5 passed about 57% of the time and 6-9-year-olds primarily passed.^[8] So, we can clearly see a developmental trajectory for this skill.

Video: False Belief Task

 

The false belief task has become a standard for assessing children’s theory of mind, but it is not the only way. Theory of Mind can be more complex than a false belief task, and there are differences in individuals’ ToM all the way through adulthood.

Gestalt Principles of Perception

In the early part of the 20th century, = Max Wertheimer, a German psychologist, was inspired by a children’s toy to publish a paper demonstrating that individuals perceived motion when watching rapidly presented still images. This is similar to how a Disney cartoon is made —photos are taken of sets of drawings, each one with a very slight difference. Then when they are presented in quick succession, it looks like the objects and people in the pictures are moving. A flip book works on the same principle. Wertheimer (along with Kohler and Koffka) used this example to demonstrate that perception involved more than combining simple sensations. We are not aware of each individual picture. Instead, we perceive something new that becomes apparent motion. This discovery led to a new movement within the field of psychology known as Gestalt psychology. The word gestalt is used to mean the “whole structure”, but its use reflects the idea that the whole perception is different from the sum of its parts. In other words, the brain creates a perception (such as motion) that is more than simply the sum of available sensory inputs (lots of static images). Gestalt psychologists discovered that visual perception depends on a number of predictable principles that the brain uses to organize sensory information. As a result, Gestalt psychology has been extremely influential in the area of sensation and perception.^[23]

 

Gestalt psychologists often used optical illusions to demonstrate the principles. For example, if we look at a picture (or a scene in the real world) we make assumptions about figure-ground relationships. Figure refers to central object(s) in the scene, while the ground refers to the background.^[24] This is one of many gestalt principles. There are audio illusions that demonstrate how our brains “fill in the blanks” of things we hear as well.

 

Link to Learning

Watch this video showing real world examples of Gestalt principles to learn more.^[25]

Or this one to learn about audio illusions that do not rely on vision.

 

 According to Gestalt theorists, our ability to discriminate among shapes and objects occurs because our brains gain experience of the world and then automatically use the Gestalt principles to interpret what we see. You probably feel fairly certain that your perception accurately matches the real world, but this is not always the case. Our perceptions are based on educated guesses. These guesses are influenced by a number of factors, including our experiences, expectations, personality, and even what we have just been doing, thinking, and feeling. So, each time we make an interpretation of the world around us, we do so with a particular perceptual set, i.e., some expectation of what we are going to perceive. Priming studies in psychology show us that it is easy to change someone’s perceptual set, simply by presenting some other stimulus prior to a perceptual task. Priming explains why it is easier to startle someone after watching a scary movie. The content of the movie changes our perceptual set.

Stereotypes and bias can also affect perceptual set and perceptual task performance. For example, the ability of non-Black participants to quickly decide whether they are looking at a picture of a gun or a tool (weapon identification task) is influenced by whether they see a picture of a Black or White male just before it (Figure 5.19). Non-Black participants identify guns faster and are more likely to identify tools as guns when the image is paired with a picture of a Black man.^[26]

Research shows that this type of bias is largely unconscious or implicit. Non-Black participants do not necessarily endorse explicitly prejudiced views toward Black and Brown people. Nevertheless, disproportionately large numbers of unarmed Black and Brown people have been killed by police officers and others claiming that they believed that the victim had a gun and/or represented some threat to their personal safety. Psychologists like Stanford Professor and recipient of the MacArthur Genius Award, Jennifer Eberhardt,^[27]and Director of the Center for Policing Equity,, Phillip Goff^[28] are fierce advocates for social justice. Both have worked with police departments to help officers recognize implicit bias and to learn strategies to reduce its impact on policing.

Link to Learning

Watch this interview^[29] with Dr. Goff and read this article^[30] about Dr. Eberhardt’s implicit bias training with police officers to learn more about the ways psychologists can influence police behaviors and training.

The beginning of human knowledge is through the senses, and the fiction writer begins where human perception begins.  – Flannery O’Connor

 

 

College As Education of your Senses

The college curriculum is designed to help you develop different perspectives with which you can understand and appreciate your life. You might take a course in art, music, or both. Such courses might be considered “education of the senses.” The fact that even bands of nomadic hunter-gatherers produce art and music suggest that there is something about our genetics which makes such activities intrinsically rewarding. Certainly, a developed appreciation of the different forms of human creativity enhances and enriches our lives.

 

College courses in art and music expose students to classic and current forms of human creativity. In the same way that reading requires constructing larger and larger “gestalts” (i.e., letters, words, phrases, sentences, etc.), the same can be true for art (lines, shapes, forms, patterns, etc.) and music (e.g., tones, chords, melodies, etc.). Your eyes and ears can be “trained” to detect elements and patterns of visual and auditory sensations. Courses in art and music analyze (i.e., determine the common elements of “good” art and music) and synthesize (i.e., relate different examples of art and art forms to each other) the creative and performing arts. In this way, such courses convey our current understanding of those defining human qualities which do not at first glance appear related to eating and surviving but rather to “What’s it all about?”

 

Links to Learning

Elements of Design: Watch this video describing the fundamental elements of design:

Music: Watch this video describing how to appreciate the five fundamental elements of music:

 

There is a saying that you get out of life what you put into it. The amount of time and effort you dedicate to any activity will influence how proficient you become. This applies to your schoolwork and grades, but the college experience provides other possibilities for developing your potential. There are usually many extra-curricular activities available for you to sustain existing hobbies and interests and explore new ones. Consider the knowledge, skills, and attitudes you would like to acquire in your immediate and long term future, and seek out opportunities that might support that skill development.

The psychology research literature can also play a valuable role in your skill development. One of the skills a professional in any field must possess is the ability to locate and evaluate research. We live in a time in which we are inundated with information from the media and the internet. Reviewing the literature can feel like searching for a needle in a haystack. Even when you think you have located relevant information, how can you be certain you can trust the source? Fortunately, most professions attempt to facilitate this process by developing peer-evaluated databases. The American Psychological Association produces PsycINFO, which lists and abstracts peer-reviewed articles dating from the 1800s. In addition to psychology research, PsycINFO covers related fields such as medicine, neuroscience, and social work. Most college libraries will have a subscription to this extremely helpful and credible database.

 

Related to sensation and perception, colleges and universities frequently have clubs or activities dedicated to art, music, food and/or wine tasting, dance and sports or other movement-related activities. There are often offices or campus units where you can obtain paid or voluntary positions requiring specialized applications of your senses. This would certainly be true if you worked as an artist for a campus newspaper or as a DJ for a college radio station. There is an old saying that there are three types of people: those who make things happen, those who watch things happen, and those who ask, “What happened?” In the same way that it is important to be an active student by trying to anticipate and answer questions based upon your course material, it is important to be active in your personal development during your college years. Try to explore your college environment, searching for growth opportunities. Try out and join interesting clubs. Attend special lectures and events. Make things happen!

 

Things do not happen. Things are made to happen. – John F Kennedy

 

 

Educate your Senses

As an example of how the psychology research literature can assist you in achieving your personal objectives, an experiment was conducted to compare two different approaches to learning to play the piano. It was found that practicing with both hands at the same time was better and more efficient than practicing with one hand at a time.^[31]  Since we now know that our brain predicts and interprets our senses and we have some control over those interpretations, you might even be able to practice re-categorizing your senses. For example, if you feel nervous or anxious and that sometimes prevents you from trying something new. If instead you can try to see those “butterflies” as determination (a brilliant sensei once said “put your butterflies into a formation,” you might be able to use those nerves to help you open up your world.

 

Another way of approaching your learning might be to practice taking the perspective of the other. Since you now know we cannot have exactly the same perspective as anyone else – literally and figuratively – can you find ways to learn about other ways of perceiving the world? How might cultivating a sense of wonder and curiosity help you?

 

In conclusion, our sensory systems play a crucial role in providing us with information about the world around us. Sensation involves the process of converting external stimuli into neural energy and transmitting it to the brain, while perception refers to the interpretation and conscious experience of sensory information. Our perception is influenced by factors such as attention, motivation, experience, biases, and culture. Studying sensation and perception provides insights into the mechanisms of sensory processing and how they shape our experiences. This knowledge is crucial for fields such as psychology, neuroscience, medicine, and design, enabling us to improve human well-being, create effective interventions, and design environments that optimize sensory experiences.

 

questions

• Describe a situation where you encountered physical pain and consider how your perception of pain was influenced by factors such as your emotional state, expectations, and the context in which the pain occurred. What helped to get you through the pain?
• Think about a time when you use one sense by itself and other times where you needed to use more than one sense at a time to do something successfully.
• Imagine you are designing a product packaging for a food item. How can you utilize principles of sensory perception, such as color, texture, and visual cues, to create packaging that not only captures attention but also enhances consumers’ perception of the product?
• How does our perception of the world differ from objective reality? Discuss the role of sensation and perception in shaping our subjective experience.
• How do cultural factors influence our perception of sensory stimuli? Give examples of how cultural norms and values can shape our interpretation of sensory information.
• Reflect on the role of illusions in studying sensation and perception. Why do illusions occur, and what do they reveal about the workings of our sensory and perceptual systems? How can illusions help us understand the limitations and biases of our perceptions?
• Reflect on the ways in which our perception of sensory stimuli can be influenced by psychological factors such as emotions, motivations, and past experiences. How might our subjective states shape our interpretation and response to sensory information?

 

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[1] (Masuda, 2017)

[2] (Masuda & Nisbett, 2006)

[3] (Marshall et al., 1963)

[4]  (Segall et al., 1966)

[5] (Segall et al., 1999)

[6] (Young et al., 2012).

[7] (Lee & Penrod, 2022)

[8] (Griffith et al., 2019),

[9] (Lee & Penrod, 2022)

[10] (McKone et al. 2019)

[11](Swets, 1964)

[12]  (Liem et al., 2004)

[13] (Woolcott et al., 1983)

[14] (Plassman et al., 2008)

[15] (Wang & Chang, 2022)

[16] (Cisneros-Franco et al., 2020)

[17] (Pascalis et al., 2020)

[18]  (Cisneros-Franco et al., 2020; Pascalis et al., 2020).

[19] Hepper, Peter G. “Human fetal “olfactory” learning.” International Journal of Prenatal and Perinatal Psychology and Medicine 7.2 (1995): 147-151.

[20] Wimmer, H., & Perner, J. (1983). Beliefs about beliefs: Representation and constraining function of wrong beliefs in young children’s understanding of deception. Cognition, 13(1), 103-128.

[21] Kidd, D. C., & Castano, E. (2013). Reading literary fiction improves theory of mind. Science, 342(6156), 377-380.

[22] Panero, M. E., Weisberg, D. S., Black, J., Goldstein, T. R., Barnes, J. L., Brownell, H., & Winner, E. (2016). Does reading a single passage of literary fiction really improve theory of mind? An attempt at replication. Journal of personality and social psychology, 111(5), e46.

[23] (Rock & Palmer, 1990)

[24] (Peterson & Gibson, 1994; Vecera & O’Reilly, 1998).

[25] Michael Britt. “Gestalt Principles of Perception – with Examples.” YouTube, 11 Sept. 2013, openstax.org/l/gestalt. Accessed 1 Aug. 2024.

[26] (Payne, 2001; Payne et al., 2005; Payne & Correll, 2020)

[27]“Jennifer Eberhardt.” Stanford.edu, 2024, www.gsb.stanford.edu/sites/default/files/styles/270_x_270/public/faculty/photo/photo-faculty-eberhardt-jennifer.jpeg.webp?itok=DF5zmrWH. Accessed 1 Aug. 2024.[28] “Center for Policing Equity – Dr. Phillip Atiba Solomon (F.k.a. Goff).” Policingequity.org, policingequity.org/about/team/executive-leadership/staff/dr-phillip-atiba-goff. Accessed 1 Aug. 2024.

[29] Hub Culture. “George Floyd Two Years on | Phillip Atiba Goff, Center for Policing Equity | Hub Culture Davos 2022.” YouTube, 28 May 2022, www.youtube.com/watch?v=PrV4P3fli-k. Accessed 19 Apr. 2023.

[30]Luscombe, Belinda. “How Police Departments Should Be Approaching Reform.” Time, 8 June 2020, time.com/5849172/police-racial-bias/.

[31] (Brown, 1933)