What is the difference between sensation and perception

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. If an audience member were to receive a text message on her cell phone which caused her screen to light up, chances are that many people would notice the change in illumination in the theater.

However, if the same thing happened in a brightly lit arena during a basketball game, very few people would notice. The cell phone brightness does not change, but its ability to be detected as a change in illumination varies dramatically between the two contexts. While our sensory receptors are constantly collecting information from the environment, it is ultimately how we interpret that information that affects how we interact with the world.

Perception refers to the way sensory information is organized, interpreted, and consciously experienced. Perception involves both bottom-up and top-down processing. Bottom-up processing refers to the fact that perceptions are built from sensory input. On the other hand, how we interpret those sensations is influenced by our available knowledge, our experiences, and our thoughts.

This is called top-down processing. One way to think of this concept is that sensation is a physical process, whereas perception is psychological. Although our perceptions are built from sensations, not all sensations result in perception.

Sensation and perception are basic phenomena in us that happen throughout our life. Sensation basically refers to the process of sensing our environment using the stimuli we obtain from our five senses, on the other hand, perception refers to the process of interpreting those stimuli to meaningful information.

Thus, perception typically follows sensation. This is the basic difference between sensation and perception. Upen, BA Honours in Languages and Linguistics, has academic experiences and knowledge on international relations and politics. Figure 1: Five Senses. Figure Perception.

View all posts. 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. Share This Book. Increase Font Size. What happened? We adapted to the constant stimulus the radio volume over the course of the previous day and increased the volume at various times.

Now that we have introduced some basic sensory principles, let us take on each one of our fascinating senses individually. Vision is a tricky matter. When we see a pizza, a feather, or a hammer, we are actually seeing light bounce off that object and into our eye. Light enters the eye through the pupil, a tiny opening behind the cornea. The pupil regulates the amount of light entering the eye by contracting getting smaller in bright light and dilating getting larger in dimmer light.

Once past the pupil, light passes through the lens, which focuses an image on a thin layer of cells in the back of the eye, called the retina. Because we have two eyes in different locations, the image focused on each retina is from a slightly different angle binocular disparity , providing us with our perception of 3D space binocular vision.

You can appreciate this by holding a pen in your hand, extending your arm in front of your face, and looking at the pen while closing each eye in turn.

Pay attention to the apparent position of the pen relative to objects in the background. Depending on which eye is open, the pen appears to jump back and forth! This is how video game manufacturers create the perception of 3D without special glasses; two slightly different images are presented on top of one another. It is in the retina that light is transduced, or converted into electrical signals, by specialized cells called photoreceptors.

The retina contains two main kinds of photoreceptors: rods and cones. Rods are primarily responsible for our ability to see in dim light conditions, such as during the night. Cones, on the other hand, provide us with the ability to see color and fine detail when the light is brighter. Rods and cones differ in their distribution across the retina, with the highest concentration of cones found in the fovea the central region of focus , and rods dominating the periphery see Figure 2.

Next, the electrical signal is sent through a layer of cells in the retina, eventually traveling down the optic nerve. Information is then sent to a variety of different areas of the cortex for more complex processing. Some of these cortical regions are fairly specialized—for example, for processing faces fusiform face area and body parts extrastriate body area. Damage to these areas of the cortex can potentially result in a specific kind of agnosia , whereby a person loses the ability to perceive visual stimuli.

A great example of this is illustrated in the writing of famous neurologist Dr. Oliver Sacks; he experienced prosopagnosia , the inability to recognize faces. Humans have the ability to adapt to changes in light conditions.

As mentioned before, rods are primarily involved in our ability to see in dim light. They are the photoreceptors responsible for allowing us to see in a dark room. You might notice that this night vision ability takes around 10 minutes to turn on, a process called dark adaptation. This is because our rods become bleached in normal light conditions and require time to recover. We experience the opposite effect when we leave a dark movie theatre and head out into the afternoon sun.

During light adaptation , a large number of rods and cones are bleached at once, causing us to be blinded for a few seconds. Light adaptation happens almost instantly compared with dark adaptation. Interestingly, some people think pirates wore a patch over one eye in order to keep it adapted to the dark while the other was adapted to the light. Our cones allow us to see details in normal light conditions, as well as color.

We have cones that respond preferentially, not exclusively, for red, green and blue Svaetichin, This trichromatic theory is not new; it dates back to the early 19th century Young, ; Von Helmholtz, This theory, however, does not explain the odd effect that occurs when we look at a white wall after staring at a picture for around 30 seconds.

Try this: stare at the image of the flag in Figure 3 for 30 seconds and then immediately look at a sheet of white paper or a wall. According to the trichromatic theory of color vision, you should see white when you do that. Is that what you experienced?

This is where the opponent-process theory comes in Hering, This theory states that our cones send information to retinal ganglion cells that respond to pairs of colors red-green, blue-yellow, black-white.