What does sensation mean in psychology

Sensory receptors are specialized neurons that respond to specific types of stimuli. When sensory information is detected by a sensory receptor, sensation has occurred. For example, light that enters the eye causes chemical changes in cells that line the back of the eye.

These cells relay messages, in the form of action potentials as you learned when studying biopsychology , to the central nervous system. The conversion from sensory stimulus energy to action potential is known as transduction. You have probably known since elementary school that we have five senses: vision, hearing audition , smell olfaction , taste gustation , and touch somatosensation.

It turns out that this notion of five senses is oversimplified. We also have sensory systems that provide information about balance the vestibular sense , body position and movement proprioception and kinesthesia , pain nociception , and temperature thermoception. The sensitivity of a given sensory system to the relevant stimuli can be expressed as an absolute threshold.

Another way to think about this is by asking how dim can a light be or how soft can a sound be and still be detected half of the time. The sensitivity of our sensory receptors can be quite amazing. Under quiet conditions, the hair cells the receptor cells of the inner ear can detect the tick of a clock 20 feet away Galanter, It is also possible for us to get messages that are presented below the threshold for conscious awareness—these are called subliminal messages.

A stimulus reaches a physiological threshold when it is strong enough to excite sensory receptors and send nerve impulses to the brain: This is an absolute threshold. A message below that threshold is said to be subliminal: We receive it, but we are not consciously aware of it. Over the years there has been a great deal of speculation about the use of subliminal messages in advertising, rock music, and self-help audio programs. Research evidence shows that in laboratory settings, people can process and respond to information outside of awareness.

Absolute thresholds are generally measured under incredibly controlled conditions in situations that are optimal for sensitivity. Sometimes, we are more interested in how much difference in stimuli is required to detect a difference between them. This is known as the just noticeable difference jnd or difference threshold.

Unlike the absolute threshold, the difference threshold changes depending on the stimulus intensity. As an example, imagine yourself in a very dark movie theater. Our perceptions can also be affected by our beliefs, values, prejudices, expectations, and life experiences. The shared experiences of people within a given cultural context can have pronounced effects on perception. For example, Marshall Segall, Donald Campbell, and Melville Herskovits published the results of a multinational study in which they demonstrated that individuals from Western cultures were more prone to experience certain types of visual illusions than individuals from non-Western cultures, and vice versa.

These perceptual differences were consistent with differences in the types of environmental features experienced on a regular basis by people in a given cultural context. In contrast, people from certain non-Western cultures with an uncarpentered view, such as the Zulu of South Africa, whose villages are made up of round huts arranged in circles, are less susceptible to this illusion Segall et al.

It is not just vision that is affected by cultural factors. In terms of color vision across cultures, research has found derived color terms for brown, orange and pink hues do appear to be influenced by cultural differences Zollinger, Sensation occurs when sensory receptors detect sensory stimuli.

Perception involves the organization, interpretation, and conscious experience of those sensations. Sensory adaptation, selective attention, and signal detection theory can help explain what is perceived and what is not. In addition, our perceptions are affected by a number of factors, including beliefs, values, prejudices, culture, and life experiences.

Not everything that is sensed is perceived. Do you think there could ever be a case where something could be perceived without being sensed? Please generate a novel example of how just noticeable difference can change as a function of stimulus intensity. Think about a time when you failed to notice something around you because your attention was focused elsewhere.

This would be a good time for students to think about claims of extrasensory perception. Another interesting topic would be the phantom limb phenomenon experienced by amputees. There are many potential examples. One example involves the detection of weight differences. If two people are holding standard envelopes and one contains a quarter while the other is empty, the difference in weight between the two is easy to detect.

However, if those envelopes are placed inside two textbooks of equal weight, the ability to discriminate which is heavier is much more difficult. Skip to content Learning Objectives By the end of this section, you will be able to: Distinguish between sensation and perception Describe the concepts of absolute threshold and difference threshold Discuss the roles attention, motivation, and sensory adaptation play in perception.

See for yourself how inattentional blindness works by checking out this selective attention test from Simons and Chabris Exercises Review Questions: 1. Personal Application Question : 1. Glossary: absolute threshold bottom-up processing inattentional blindness just noticeable difference perception sensation sensory adaptation signal detection theory subliminal message top-down processing transduction. Answers to Exercises Review Questions: 1. B Critical Thinking Question: 1.

Previous Section. Next Section. License 5. What about the height of a sound? If both ears receive a sound at the same time, how are we capable of localizing sound vertically?

After being processed by auditory hair cells, electrical signals are sent through the cochlear nerve a division of the vestibulocochlear nerve to the thalamus, and then the primary auditory cortex of the temporal lobe.

Information from the vestibular system is sent through the vestibular nerve the other division of the vestibulocochlear nerve to muscles involved in the movement of our eyes, neck, and other parts of our body. This information allows us to maintain our gaze on an object while we are in motion.

Disturbances in the vestibular system can result in issues with balance, including vertigo. Who actually enjoys having sand in their swimsuit? Somatosensation —which includes our ability to sense touch, temperature and pain—transduces physical stimuli, such as fuzzy velvet or scalding water, into electrical potentials that can be processed by the brain.

Tactile stimuli —those that are associated with texture—are transduced by special receptors in the skin called mechanoreceptors. Just like photoreceptors in the eye and auditory hair cells in the ear, these allow for the conversion of one kind of energy into a form the brain can understand.

After tactile stimuli are converted by mechanoreceptors, information is sent through the thalamus to the primary somatosensory cortex for further processing. Put simply, various areas of the skin, such as lips and fingertips, are more sensitive than others, such as shoulders or ankles. This sensitivity can be represented with the distorted proportions of the human body shown in Figure 5. Without pain, how would we know when we are accidentally touching a hot stove, or that we should rest a strained arm after a hard workout?

Records of people experiencing phantom limbs after amputations have been around for centuries Mitchell, As the name suggests, people with a phantom limb have the sensations such as itching seemingly coming from their missing limb.

A phantom limb can also involve phantom limb pain , sometimes described as the muscles of the missing limb uncomfortably clenching. There is an interesting treatment for the alleviation of phantom limb pain that works by tricking the brain, using a special mirror box to create a visual representation of the missing limb. The two most underappreciated senses can be lumped into the broad category of chemical senses.

Both olfaction smell and gustation taste require the transduction of chemical stimuli into electrical potentials. I say these senses are underappreciated because most people would give up either one of these if they were forced to give up a sense.

Many of us pay a lot more for a favorite brand of food because we prefer the taste. Clearly, we humans care about our chemical senses. Unlike any of the other senses discussed so far, the receptors involved in our perception of both smell and taste bind directly with the stimuli they transduce. Odorants in our environment, very often mixtures of them, bind with olfactory receptors found in the olfactory epithelium. The binding of odorants to receptors is thought to be similar to how a lock and key operates, with different odorants binding to different specialized receptors based on their shape.

Regardless of how odorants bind with receptors, the result is a pattern of neural activity. It is thought that our memories of these patterns of activity underlie our subjective experience of smell Shepherd, Interestingly, because olfactory receptors send projections to the brain through the cribriform plate of the skull, head trauma has the potential to cause anosmia , due to the severing of these connections.

If you are in a line of work where you constantly experience head trauma e. Taste works in a similar fashion to smell, only with receptors found in the taste buds of the tongue, called taste receptor cells.

To clarify a common misconception, taste buds are not the bumps on your tongue papillae , but are located in small divots around these bumps. These receptors also respond to chemicals from the outside environment, except these chemicals, called tastants , are contained in the foods we eat. The binding of these chemicals with taste receptor cells results in our perception of the five basic tastes: sweet, sour, bitter, salty and umami savory —although some scientists argue that there are more Stewart et al.

Researchers used to think these tastes formed the basis for a map-like organization of the tongue; there was even a clever rationale for the concept, about how the back of the tongue sensed bitter so we would know to spit out poisons, and the front of the tongue sensed sweet so we could identify high-energy foods.

During the process of eating we are not limited to our sense of taste alone. While we are chewing, food odorants are forced back up to areas that contain olfactory receptors. This combination of taste and smell gives us the perception of flavor. If you have doubts about the interaction between these two senses, I encourage you to think back to consider how the flavors of your favorite foods are impacted when you have a cold; everything is pretty bland and boring, right?

Though we have spent the majority of this module covering the senses individually, our real-world experience is most often multimodal, involving combinations of our senses into one perceptual experience.

This should be clear after reading the description of walking through the forest at the beginning of the module; it was the combination of senses that allowed for that experience. Information from one sense has the potential to influence how we perceive information from another, a process called multimodal perception. During the video, a person dressed in a black gorilla costume walks among the two teams.

You would think that someone would notice the gorilla, right? Because participants were so focused on the number of times the white team was passing the ball, they completely tuned out other visual information. Failure to notice something that is completely visible because of a lack of attention is called inattentional blindness.

In a similar experiment, researchers tested inattentional blindness by asking participants to observe images moving across a computer screen. They were instructed to focus on either white or black objects, disregarding the other color. Read more on inattentional blindness at the Noba Project website.

Figure 6. Nearly one third of participants in a study did not notice that a red cross passed on the screen because their attention was focused on the black or white figures. Motivation can also affect perception. Have you ever been expecting a really important phone call and, while taking a shower, you think you hear the phone ringing, only to discover that it is not? If so, then you have experienced how motivation to detect a meaningful stimulus can shift our ability to discriminate between a true sensory stimulus and background noise.

The ability to identify a stimulus when it is embedded in a distracting background is called signal detection theory. This might also 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 increasing air traffic controller accuracy. Controllers need to be able to detect planes among many signals blips that appear on the radar screen and follow those planes as they move through the sky.

In fact, the original work of the researcher who developed signal detection theory was focused on improving the sensitivity of air traffic controllers to plane blips Swets, Our perceptions can also be affected by our beliefs, values, prejudices, expectations, and life experiences.

The shared experiences of people within a given cultural context can have pronounced effects on perception. For example, Marshall Segall, Donald Campbell, and Melville Herskovits published the results of a multinational study in which they demonstrated that individuals from Western cultures were more prone to experience certain types of visual illusions than individuals from non-Western cultures, and vice versa.

Figure 7. These perceptual differences were consistent with differences in the types of environmental features experienced on a regular basis by people in a given cultural context.

In contrast, people from certain non-Western cultures with an uncarpentered view, such as the Zulu of South Africa, whose villages are made up of round huts arranged in circles, are less susceptible to this illusion Segall et al.

It is not just vision that is affected by cultural factors. Privacy Policy. Skip to main content. Module 5: Sensation and Perception. Search for:. Sensation What does it mean to sense something? Try It. Think It Over Think about a time when you failed to notice something around you because your attention was focused elsewhere. Watch It See for yourself how inattentional blindness works by watching this selective attention test from Simons and Chabris :.