How does sensation becomes perception

Sensation is a function of the low level, biochemical, and neurological mechanisms that allow the receptor cells of a sensory organ to detect an environmental stimulus. Color optical illusion : The brain interprets the pink cube on the light gray background as being a darker shade than the pink cube on the dark gray background.

In other words, the goal of sensation is detection, while the goal of perception is to create useful information about the environment. Stimuli from the environment distal stimuli are transformed into neural signals, which are then interpreted by the brain through a process called transduction. Transduction can be likened to a bridge connecting sensation to perception. This raw pattern of neural activity is called the proximal stimulus.

The neural signals are transmitted to the brain and processed. Signals follow the same pathways the brain as when the appendage existed. Problem - studies have shown that when areas in the spinal cord are severed often feelings still being perceived from areas that meet the spinal cord in lower areas below separation in spinal cord. This has been expanded - brain contains a network of fibers that not only respond to stimulation but continually generates a pattern of impulses that indicate that the body is intact and functioning.

Thus, the brain creates the impression that the limb exists and is al right. This system may be prewired. Although many theories exist for this illusion, there is no certain explanation. One theory is based on eye movement. When the arrows point inwards, our gaze rests inside the angles formed by the arrows. When they point outwards, our eyes demarcate the entire perspective and our gaze rests outside the angles.

The outward pointing arrows make the figure more open and so the horizontal line appears longer. He himself attempted to explain the illusion he had discovered as follows: "the judgment not only takes the lines themselves into consideration, but also, unintentionally, some part of the space on either side. He noticed that in many cases, the figure had been drawn the wrong way round so that the illusion appeared more forceful!

Sensations and Perceptions Sensations can be defined as the passive process of bringing information from the outside world into the body and to the brain. Color Vision Theories: 1 Trichromatic Theory - this theory indicates that we can receive 3 types of colors red, green, and blue and that the cones vary the ratio of neural activity Like a projection T. A Gestalt Principles of Perceptual Organization 1 figure-ground - this is the fundamental way we organize visual perceptions.

B Illusions - an incorrect perception caused by a distortion of visual sensations. There are two different pathways to the brain on which pain can travel - information brought from free nerve endings in the skin to the brain via two different systems: 1 fast pathways - registers localized pain usually sharp pain and sends the information to the cortex in a fraction of a second. Factors in Pain Perception - not an automatic result of stimulation: 1 expectations - research shown that our expectations about how much something will hurt can effect our perception.

Melzack - indicated that believing that something will be very painful helps us prepare for it. E For example - a very uptight person may experience muscle pains, back pains, etc. So, it seems that our brains can regulate, control, determine, and even produce pain. There are two types of nerve fibers in this area: a large - sends fast signals and can prevent pain by closing the gate. Contradiction to Gate Control Theory: 1 endorphins - the body's own pain killers morphine-like.

Go to Phantom Limb Pages - includes case studies Explanations: 1 the neuroma explanation - remaining nerves in the stump grow into nodules neuromas at the end of the stump continue to fire signals. Please note that we can not cover ALL the senses in class so make sure you read about taste, touch, hearing, and smell in the book. 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. This motivational aspect of expectation in conversation additionally may be why such strong inattentional blindness has been found in relation to cell phone use. The ability to identify a stimulus when it is embedded in a distracting background is called signal detection theory.

Signal detection theory: A theory explaining explaining how various factors influence our ability to detect weak signals in our environment. Signal detection theory also explains why a mother is awakened by a quiet murmur from her baby but not by other sounds that occur while she is asleep. This also applies to air traffic controller communication, pilot and driver control panels as discussed previously, and even the monitoring of patient vital information while a surgeon performs surgery.

In the case of air traffic controllers, the 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.

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.

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. Figure 2. Priming can be used to improve intellectual test performance. Research subjects primed with the stereotype of a professor — a sort of intellectual role model — outperformed those primed with an anti-intellectual stereotype.

These days, most scientific research on unconscious processes is aimed at showing that people do not need consciousness for certain psychological processes or behaviors. One such example is attitude formation.

The most basic process of attitude formation is through mere exposure Zajonc, Merely perceiving a stimulus repeatedly, such as a brand on a billboard one passes every day or a song that is played on the radio frequently, renders it more positive.

Interestingly, mere exposure does not require conscious awareness of the object of an attitude. In fact, mere-exposure effects occur even when novel stimuli are presented subliminally for extremely brief durations e. Intriguingly, in such subliminal mere-exposure experiments, participants indicate a preference for, or a positive attitude towards, stimuli they do not consciously remember being exposed to.

Another example of modern research on unconscious processes is research on priming. Priming generally relies on supraliminal stimuli, which means that the messaging may occur out of awareness, but it is still perceived, unlike subliminal messaging. Supraliminal messages are be perceived by the conscious mind. For example, in one study, shoppers listened to either French or German music the supraliminal messaging while buying wine, and sales originating from either country were higher when music from that same country was played overhead.

These lists contained words commonly associated with the elderly e. The remaining participants received a language task in which the critical words were replaced by words not related to the elderly. After participants had finished they were told the experiment was over, but they were secretly monitored to see how long they took to walk to the nearest elevator.

The primed participants took significantly longer. That is, after being exposed to words typically associated with being old, they behaved in line with the stereotype of old people: being slow. Such priming effects have been shown in other domains as well. For example, Dijksterhuis and van Knippenberg demonstrated that priming can improve intellectual performance.

They asked their participants to answer 42 general knowledge questions taken from the game Trivial Pursuit. Both of these studies have had difficult times replicating, so it is worth noting that the conclusions reached may not be as powerful as originally reported. 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.