.This is an information from the chapter to help you to write the essay. Our bodies are bombarded with information during wakefulness and sleep. This information takes many forms, from the electromagnetic energy of the sun to vibrations in the air to molecules dissolved in saliva on our tongues. The process of sensation brings information to the brain that arises in the reality outside our bodies, like a beautiful sunset, or originates from within, like an upset stomach. Sensory systems have been shaped by natural selection, described in Chapter 3, to provide information that enhances survival within a particular niche. We sense a uniquely human reality, and one that is not shared by other animals. Your dog howls seconds before you hear the siren from an approaching ambulance because the dogs hearing is better than yours for high-pitched sounds. Horses bolt at the slightest provocation, but they may be reacting to the vibration of an approaching car or an animal that they sense through their front hooves, a source of information that is not available to the rider. Some animals sense light energy outside the human visible spectrum. Insects can see ultraviolet light, and some snakes use infrared energy to detect their prey. Differences in sensation do occur from person to person, such as the need to wear corrective glasses or not, but they are relatively subtle. However, once we move from the process of sensation to that of perception , or the interpretation of sensory input, individual differences become more evident. For example, friends voting for different presidential candidates will come to different conclusions about who won a debate. Everyone watching the exchange sensed similar information, but each persons perceptions are unique. Sensory Information Travels to the Brain . Sensation begins with the interaction between a physical stimulus and our biological sensory systems. A stimulus is anything that elicits a reaction from our sensory systems. For example, we react to light energy that falls within our visual range, as we will see later in this chapter, but we cannot see light energy that falls outside that range, such as the microwaves that cook our dinner or the ultraviolet waves that harm our skin (see Figure 5.1). Before you can use information from your senses, it must be translated into a form the nervous system can understand. This process of translation from stimulus to neural signal is known as transduction . You might think of sensory transduction as being similar to the processing of information by your computer. Modern computers transduce a variety of inputs, including voice, keyboard, mouse clicks, and touch, into a programming language for further processing. We have all had the experience of watching events with others (sensation) and then being shocked by the different interpretations we hear of what just happened (perception). The Brain Constructs Perceptions from Sensory Information . Once information from the sensory systems has been transduced into neural signals and sent to the brain, the process of perception, or the interpretation of the sensory information, begins. Perception allows us to organize, recognize, and use the information provided by the senses. If you think about the most memorable advertisements you have seen lately on television or online, it is likely that they share the features of attention-getting stimuli: novelty (we dont see talking geckos every day), change (rapid movement, use of changing colors, and the dreaded pop-up), and intensity (the sound is often louder than the program youre watching). . An important gateway to perception is the process of attention, defined as a narrow focus of consciousness. As we discuss in Chapters 6, 9, and 10, attention often determines which features of the environment influence our subsequent thoughts and behaviors. Which stimuli are likely to grab our attention? Unfamiliar, changing, or high-intensity stimuli often affect our survival and have a high priority for our attention. Unfamiliar stimuli in our ancestors environment might have meant a new source of danger (an unknown predator) or a new source of food (an unfamiliar fruit) that warranted additional investigation. Our sensory systems are particularly sensitive to change in the environment. Notice how you pay attention to the sound of your heating system cycling on or off but pay little attention to the noise it makes while running. This reduced response to an unchanging stimulus is known as sensory adaptation . High-intensity stimuli, such as bright lights and loud noises, draw our attention because the situations that produce these stimuli, such as a nearby explosion, can have obvious consequences for our safety. We rarely have the luxury of paying attention to any single stimulus. In most cases, we experience divided attention, in which we attempt to process multiple sources of sensory information. Students walk to class without getting run over by a car while texting. These divided attention abilities are limited. We simply cannot process all the information converging simultaneously on our sensory systems. To prioritize input, we use selective attention or the ability to focus on a subset of available information and exclude the rest. These abilities may be disrupted in cases of attention deficit hyperactivity disorder (ADHD; Wimmer et al., 2015; also see Chapter 14). We refer to the brains use of incoming signals to construct perceptions as bottom-up processing . For example, we construct our visual reality from information about light that is sent from the eye to the brain. However, the brain also imposes a structure on the incoming information, a type of processing known as top-down. In top-down processing , we use knowledge gained from prior experience with stimuli to perceive them. For example, a skilled reader has no trouble reading the following sentences, even though the words are jumbled: All you have to do to make a sentence readable is to make sure that the first and last letters of each word stay the same. With practice, this process becomes much faster and easier. Divided attention abilities are limited. Some people believe that heads-up displays for cars assist drivers with divided attention, while others believe the displays are too distracting. Write 200-word essay of this Writing Assignment topic. Writing Assignment Topic #1. Chapter 5: Sensation and Perception. We dont merely sense the world as it is; we perceive it. Why can two people observe the same event and perceive it quite differently?
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