2. Sensory Systems

The topics of sensation and perception are among the oldest and most important in all of psychology. People are equipped with senses such as sight, hearing and taste that help us to take in the world around us. Amazingly, our senses have the ability to convert real-world information into electrical information that can be processed by the brain. The way we interpret this information — our perceptions — is what leads to our experiences of the world.

Sensation is the awareness resulting from the stimulation of a sense organ, and perception is the organization and interpretation of sensations. Sensation and perception work seamlessly together to allow us to experience the world through our sensory receptors (our eyes, ears, nose, tongue, and skin) but also to combine what we are currently learning from the environment with what we already know about it to make judgments and to choose appropriate behaviours.

Sensory Systems

Humans possess powerful sensory capacities that allow us to sense the kaleidoscope of sights, sounds, smells, and tastes that surround us. Our eyes detect light energy and our ears pick up sound waves. Our skin senses touch, pressure, hot, and cold. Our tongues react to the molecules of the foods we eat, and our noses detect scents in the air. The human perceptual system is wired for accuracy, and people are exceedingly good at making use of the wide variety of information available to them (Stoffregen & Bardy, 2001).

The eyes, ears, nose, tongue, and skin sense the world around us, and in some cases perform preliminary information processing on the incoming data. But by and large, we do not experience sensation — we experience the outcome of perception, the total package that the brain puts together from the pieces it receives through our senses and that the brain creates for us to experience. When we look out the window at a view of the countryside, or when we look at the face of a good friend, we don’t just see a jumble of colours and shapes — we see, instead, an image of a countryside or an image of a friend (Goodale & Milner, 2006).

Sensory Receptors: Seeing

Whereas other animals rely primarily on hearing, smell, or touch to understand the world around them, human beings rely primarily on vision. A large part of our cerebral cortex is devoted to seeing, and we have substantial visual skills. Seeing begins when light falls on the eyes, initiating the process of transduction. Once this visual information reaches the visual cortex, it is processed by a variety of neurons that detect colours, shapes, and motion, and that create meaningful perceptions out of the incoming stimuli.

It has been estimated that the human visual system can detect and discriminate among seven million colour variations (Geldard, 1972), but these variations are all created by the combinations of the three primary colours: red, green, and blue. The shade of a colour, known as hue, is conveyed by the wavelength of the light that enters the eye (we see shorter wavelengths as more blue and longer wavelengths as more red), and we detect brightness from the intensity or height of the wave (bigger or more intense waves are perceived as brighter).

Colour has always appealed to our visual senses and is commonly used as a marketing tool. It has a powerful psychological impact on consumers’ behaviours and choices: studies have shown that particular colours simulate certain areas of the brain to promote excitement (DashBurst, 2018). Colour can often be the main reason a consumer purchases a product or service.

Have you ever wondered why the colour red is associated with Coke, while Facebook is blue? Depending on the brand, its position in the market, and the feelings it wants to evoke in its consumers, colour choice is serious business and not to be done without considerable thought and care.

As expressed in Dashburst’s 2018 article, “McDonald’s chooses high-energy colors like red & yellow which appeal to children, kindle appetites and create a sense of urgency. Of course, Ronald McDonald himself is popular with the kids, but he’s also sure to agitate parents quickly. This facilitates faster customer turnover” (Dashburst, 2018).

On the other hand, Starbucks and its infamous use of green conveys a sense of “relaxation in their cafes, inviting customers to come in for a coffee break during a stressful day” (Dashburst, 2018).

Clearly, choosing the “right” colours for a brand requires consideration of the kind of experience a brand wants to have with its consumers.

Jesse Richardson, in his article, “3 Principles for High Conversions on Your Website” (2015), provides a brief summary of what many popular brand colours represent:

Colours are also highly characteristic and represented in different cultures; psychological effects and interpretations vary depending on the specific culture. A colour can have powerful influence on religious beliefs, politics, and art (Velarde, n.d.). For example, in the United States, the colour pink can often by synonymous with femininity and thus stereotypical representations of hyper-femininity such as princesses and ballet dancers. Conversely, in Japan, pink has a “masculine association,” according to Kate Smith (n.d.). “The annual spring blooming of the pink-blossomed cherry trees (the Sakura) is said to represent the young Japanese warriors who fell in battle in the prime of life (the Samurai; Smith, n.d.).

In many Asian, and particularly Chinese cultures, the colour red is strongly association with important cultural rituals and celebrations, such as marriage. It’s a sign of success and happiness. In South Africa, however, red represents mourning, grief, and sadness.

Sensory Receptors: Hearing

Like vision and all the other senses, hearing begins with transmission. Sound waves that are collected by our ears are converted into neural impulses, which are sent to the brain where they are integrated with past experience and interpreted as the sounds we experience. The human ear is sensitive to a wide range of sounds, from the faint tick of a clock in a nearby room to the roar of a rock band at a nightclub, and we have the ability to detect very small variations in sound. But the ear is particularly sensitive to sounds in the same frequency as the human voice. A mother can pick out her child’s voice from a host of others, and when we pick up the phone we quickly recognize a familiar voice. In a fraction of a second, our auditory system receives the sound waves, transmits them to the auditory cortex, compares them to stored knowledge of other voices, and identifies the caller.

Sensory Receptors: Tasting

Taste is important not only because it allows us to enjoy the food we eat, but, even more crucial, because it leads us toward foods that provide energy (sugar, for instance) and away from foods that could be harmful. Many children are picky eaters for a reason — they are biologically predisposed to be very careful about what they eat. Together with the sense of smell, taste helps us maintain appetite, assess potential dangers (such as the odour of a gas leak or a burning house), and avoid eating poisonous or spoiled food.

Our ability to taste begins at the taste receptors on the tongue. The tongue detects six different taste sensations, known respectively as sweet, salty, sour, bitter, piquancy (spicy), and umami (savory).

Sensory Receptors: Smelling

We have approximately 1,000 types of odour receptor cells (Bensafi et al., 2004), and it is estimated that we can detect 10,000 different odours (Malnic, Hirono, Sato, & Buck, 1999). The receptors come in many different shapes and respond selectively to different smells. Like a lock and key, different chemical molecules fit into different receptor cells, and odours are detected according to their influence on a combination of receptor cells. Just as the 10 digits from 0 to 9 can combine in many different ways to produce an endless array of phone numbers, odour molecules bind to different combinations of receptors, and these combinations are decoded in the olfactory cortex. The sense of smell peaks in early adulthood and then begins a slow decline. By ages 60 to 70, the sense of smell has become sharply diminished. In addition, women tend to have a more acute sense of smell than men.

Sensory Receptors: Touching

The sense of touch is essential to human development. The skin, the largest organ in the body, is the sensory organ for touch. The skin contains a variety of nerve endings, combinations of which respond to particular types of pressures and temperatures. When you touch different parts of the body, you will find that some areas are more ticklish, whereas other areas respond more to pain, cold, or heat.