For your Midterm essay exam, you will complete 10 essay questions that focus on the course readings. Midterm essay answers must be attached as a Word document to the appropriate assignment page, not typed into the assignment student comments boxes. In addition to writing a 300 word answer, each essay question must include APA formatted citations and references (APA title page and reference page are required. Each question should be answered clearly and numbered). Students will answer each question thoroughly and completely, providing examples where required.

Answer the questions below in your Midterm exam.

Describe the process of perception as a series of steps, beginning with the environmental stimulus and culminating in the behavioral responses of perceiving, recognizing, and acting.
Because the long axons of neurons look like electrical wires, and both neurons and electrical wires conduct electricity, it is tempting to equate the two. Compare and contrast the functioning of axons and electrical wires in terms of their structure and the nature of the electrical signals they conduct.
What are the two answers (one “simple” and the other “profound”) to the question, “Why is our perception of colors and details worse in dim illumination than in bright illumination?”
What is inference? Describe Hermann von Helmholtz’s Theory of Unconscious Inference. Compare and contrast the likeilhood principle with unconscious inference listing three similarities and three differences.
When you walk from outside, which is illuminated by sunlight, to inside, which is illuminated by “tungsten” illumination, your perception of colors remains fairly constant. But under some illuminations, such as street lights called “sodium vapor” lights that sometimes illuminate highways or parking lots, colors do seem to change. Why do you think color constancy would hold under some illuminations, but not others?
What is sensory adaptation? How does it occur within the various senses? What function does sensory adaptation serve? Provide a relevant example that illustrates your point.
What are the characteristics of the energy that we see as visible light? Provide an example illustrating how these characteristics are expressed when someone sees a rainbow. What types of things (situations and/or objects) can interfere with these characteristics?
How does the eye transduce light energy into a neural message? What is the blind spot in the eye and how does it impact the transduction of light energy?
How is visual information processed in the brain? What are some things (situations and/or objects) which can impede visual information being processed in the brain? Please include a relevant example to illustrate your answer.
List the five filtering techniques of visual attention. Identify two similarities and two differences for each of the filtering techniques. Lastly, provide an example for each filtering techniques.  Mid-Term Essay Exam Essay Example

Mid-Term Essay Exam
1. The way one understands and makes sense of the environment around them is referred to as perception. Triggers that affect a person’s various senses make this possible. Sight, hearing, touch, smell, and taste are among them. It’s also important to consider how a person mixes these senses. Thus the cognitive and psychological process that is made up of selection, organization, and interpretation of information is the one that is referred to as perception. Select stimuli travel via our perceptual receptors, are organized and arranged into our present anatomical and constitutional structures and pathways, and are then given meaning depending on earlier memories and activities (Lumen, n.d-a.).
Although our sense organs are continually collecting data from the environment, how we interpret that data ultimately determines how we engage with the environment. The way sensory data is organized, analyzed, and consciously experienced is referred to as perception. Bottom-up and top-down processes are both involved in perception. Perceptions are formed through sensory input, which is referred to as bottom-up processing. Our accessible knowledge, experiences, and thoughts, on the other hand, influence how we perceive such sensations. This is known and described as top-down processing. Although feelings are the foundation of our perceptions, not all sensations result in perception. In reality, humans frequently fail to notice stimuli that are generally steady over lengthy periods of time. Sensory adaptation is the term for this (Lumen, n.d-a.).
The perceptual process starts with our receiving environmental stimuli and finishes with our interpretation of those inputs. Choice, arrangement, and interpretation are the three steps of perception. We choose stimuli that attract our attention in the first step of selection. In the second step the data is organized into meaningful tranches; while in the third phase its meaning is derived through interpretation. The collecting of input from sensory inputs to the interpretation made by the person’s brain is all part of perception. Perception is so much more than merely absorbing random information from the outside (Lumen, n.d-a.).
2. Neurons, which are specialized cells that can collect and send chemical or electrochemical impulses, and glia, which provide support services for them, make up the nervous system. A neuron is similar to an electrical line in a building in that it conveys information from one location to the next. But that is where the similarities end. Glia are comparable to the employees at the electricity provider who ensure that lines are routed correctly, maintain the wires, and remove damaged cables. Glia therefore nourish and protect neurons and may potentially have a role in some of the signaling processes of neurons, according to new research (Tortora & Derrickson, 2014).

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Electrical and chemical signals are used by neurons to interact. Action potentials are electrical impulses that transmit signals from one neuron to the next; neurotransmitters are chemical signals that transmit information from one neuron to the next. The act of sodium ions (N+) migrating inside a neuron and potassium ions (K+) shifting in the opposite direction results in the creation of an action potential. This is a quick, brief shift in membrane potential or electrical charge. Proteinous biochemical substances called neurotransmitters are the chemical messengers released by one neuron in response to an action potential. These create a quick, brief shift in the membrane potential of a nearby neuron, causing that neuron to generate an action potential or electrical impulse (Tortora & Derrickson, 2014). The difference between neurons and electrical wires however is in the fact that the former are made up of living cells in the human body while the latter are made of artificial dead elements. A neuron not only transmits but can also generate an action potential; whereas an electrical wire has no such capacity. It is just a conveyor of electricity that is generated elsewhere through an entirely different process. These are the main contrasts between the two.
3. There is a simple answer as to why human perception of colors and other details in dim light is poor as opposed to a setting with bright illumination. It is that in dim lighting there is less light that can be reflected from objects back to the photoreceptor cells in the retina of the eye. As a consequence, the brain does not “see” the colors since it cannot interpret the darkness correctly. When there is bright light, however, all the details of an object are reflected by the light to the retina of the eye. There, the photoreceptor cells convert the stimulus into electrical impulses that are then carried by the optic nerve (the second cranial nerve) to the visual area at the back of the brain (NEI, 2019).
The “profound” or more complex answer to the same question above is that color discrimination in different lighting conditions is influenced not only by receptor noise, but also by photoreceptor interactions (Kelber et al., 2017). Color discernment is limited by receptor noise and is predicated on antagonist photoreceptor interactions. Photon shot noise affects color vision in weak light, and dark noise in cones sets the absolute color vision threshold in vertebrates. Even in very poor light, nocturnal insects like moths and nocturnal bees, as well as vertebrates without rods like geckos, have evolved to reduce receptor noise and use chromatic vision. When noisy cone signals become unreliable, vertebrates with duplex retinae switch to color-blind rod vision, and the Purkinje shift marks the transition from cone to rod vision. Color vision in dim light has not been shown to be improved by rod-cone interrelationships, but they may lead to color vision in mesopic brightness. Even at their visual limit, frogs and toads with two types of rods employ opponent signals from these rods to govern phototaxis. However, similar to other vertebrates, their color discriminating capabilities diminish at higher light intensities for functions such as prey or partner choosing, owing to dark noise in cones (Kelber et al., 2017).
4. Inferences are incomplete parts of information that a person factors in using past knowledge, hypotheses, or beliefs. If somebody enters a room and notices that the digital clocks are blinking, they can conclude or infer that there has been a recent power failure. Unconscious inference (UI) is the idea that judgments about present sensory data are affected implicitly by the perceiver’s understanding of the universe and previous experience with similar information. It is a component of Hermann von Helmholtz’s visual perception hypothesis, which was first proposed in Germany. This hypothesis proposes that human eyesight is imperfect, and that the unconscious mind infers information to form a comprehensive image. Motion and depth awareness are two of the inferences the brain makes based on the eye’s perception. Many of us have had the feeling of thinking that we see trees or structures shimmering or moving, or that buildings or summits appear nearer than they really are, due to the effects of atmospheric conditions and/or range. Hermann Ludwig Ferdinand von Helmholtz was a late 1800s German doctor, philosopher, and physicist who realized fundamental achievements in contemporary physiology and psychology with his study on the eye, vision concepts, and audio awareness (AlleyDog.com, 2021).
Other sensory categories can also be explained using the notion of unconscious inference. The scenario of an individual whose limb has been amputated is a stunning example of a significant premise abruptly becoming erroneous. According to the likelihood principle (LP), we view our surroundings in the most likely way possible based on our prior experiences. According to Helmholtz, in addition to the likelihood principle, there is a process known as unconscious inference, in which our impressions are developed based on unconscious preconceptions (Schultz, 2017). The parallels between the two are that they are both psychological theories, that they were proposed by the same professor, and that they both act at the cognitive level. The contrasts are that in UI, judgments are influenced by prior experience and knowledge of the environment, whereas in LP, judgments are based on how likely a fact may have occurred based on previous experiences.  Mid-Term Essay Exam Essay Example

5. The amount of light rebounded from an item to the eye is determined by the surface reflectance of the object as well as the illuminant. The interaction of surface and illuminant qualities causes confusion in the retinal image because many different combinations of reflectance and illuminant create the same reflected light. The visual cortex must distinguish the confused contributions of reflectance and illuminant to generate a color experience that gives trustworthy information about object attributes. The visual system has attained color constancy when it does so efficiently. Variations in the range of the lighting that impinges on an object’s surface can be caused by a variety of physical processes. One is a shift in the range of the light source used to illuminate the area. This is known as a light source adjustment. A shift in light source often has a linked effect on multiple image places (Delahunt & Brainard, 2004).
Even when the light source is kept constant, the light impinging on an object’s surface might alter. If the illumination is directional, changing the location or posture of an object, for example, can change the lighting. Another one happens when the reflectance of a surface in the scene changes. This is referred to as a reflected light change because it can adjust lighting reflected indirectly onto an item of interest. The range of the lighting that intrudes on a surface can be altered by several physical laws (Delahunt & Brainard, 2004). When making such modifications, two factors are taken into account. The first is a shift in the range of the source of light used to illuminate the scene, or a modification in the light source itself. A shift in reflectance of a surface near a sample surface of relevance, or reflected light change, is the second. Changes generated by both of these physical processes must be compensated for by a color constant visual system (Delahunt & Brainard, 2004).
6. Although feelings are the foundation of our perceptions, not all sensations result in perception. In reality, humans frequently fail to notice stimuli that are generally steady over lengthy periods of time. Sensory adaptation is the term for this (Lumen, n.d-a.). Sensory systems adjust their reactions all the time to meet the present environment. These modifications take place at multiple levels of the system, and they progressively seem to be calibrating even for very conceptual perceptual impressions of the input. The consistent adaptation effects across a wide range of input areas suggest to shared design principles, but they also raise doubts regarding adaptation’s purpose. Sensory systems that we employ to evaluate the environment around us are dynamic, constantly adjusting to account for environmental changes or correct for changes in the observer. The fragrances that entice you into a place, for example, disappear swiftly from awareness once you’re inside, yet your perception of color can shift substantially based on the colors you have seen before. Adaptation, or changes in the response characteristics of neurons generated by the recent input context, is the term for these fast sensitivity alterations. They claim that most of our visual experience is influenced by the stimuli we have previously encountered (Webster, 2012).
Sensory adaptation is defined as a decrease in sensitivity to a stimuli following repeated exposure. While sensory adaptation helps us become less aware of a continual input, it also helps us focus our attention and resources on other cues in our surroundings. Sensory adaptation can occur in all five of our senses. Our senses are always adjusting to what’s going on around us, as well as to ourselves and what we’re going through, such as age or disease. Sensory adaptation protects the senses and the brain from being overloaded with sensory stimuli, which could cause dysfunction. Suppose that no sensory adaptation occurred (Webster, 2012). For example, the aroma of prepared food emanating from the kitchen or the noise of the television coming from the living room might overwhelm them. We are able to transfer our attention to other things in our surroundings rather than concentrating on one overpowering sensation because frequent exposure to a sensory stimulation diminishes our responsiveness to it (Webster, 2012).
7. One method through which energy goes around is through visible light. Light rays are a type of electromagnetic (EM) radiation that results from the oscillations of electric and magnetic fields. Although visible light is simply one of many kinds of EM radiation and only covers a small portion of the broader electromagnetic spectrum, it holds unique relevance for us because we can see it with our eyes. The wavelengths of light waves range from 400 to 700 nanometers. Different wavelengths of light are seen by our eyes as different color colours in the rainbow. The wavelengths of red light are roughly 700 nanometers long. Short waves, around 400 nm, characterize blue and purple light. Shorter waves have more energy and resonate at higher frequencies. The frequency of red light is roughly 430 terahertz, while the frequency of blue light is closer to 750 terahertz. Each photon of red light communicates around 1.8 electron volts of energy, while each photon of blue light transmits about 3.1 eV (UCAR, 2018). On the electromagnetic spectrum, visible light is surrounded on one side by infrared radiation and on the other by ultraviolet radiation. Because infrared light has longer waves than red light, it has a lower frequency and contains less energy. Because ultraviolet light has shorter waves than blue or violet light, it oscillates faster and carries more energy per photon than visible light.
The speed of light is about 299,792 km/s. All electromagnetic waves travel at the speed of light, including X-rays, radio waves, and all other frequencies in the electromagnetic spectrum. Due to resistance, light travels the fastest in a vacuum and slightly slower in materials like water or glass. Light bends or alters course when it travels from one material to another with a different density. Light bends in different ways depending on its color. Blue light distorts significantly more than red light when it travels through a dense glass prism from the air. A prism does this by splitting white light into a rainbow of hues. When sunlight flows through raindrops, they can transform into natural prisms, resulting in rainbows (UCAR, 2018).
8. The retina at the back of the eye receives light as it enters the visual system through the eye. The rods and cones in the retina are specialized cells that convert light energy into neuronal activity. When light enters these pigments, they change shape, triggering a domino effect in the photoreceptors. The rods and cones are where light is converted into a brain signal. Photopigments, which are compounds that undergo a chemical change when they absorb light, are found in both rods and cones. Rhodopsin, the major photopigment in vertebrates, is divided into two components. One is an opsin, a membrane protein, and the other is retinal, a light-absorbing molecule. When light strikes a photoreceptor, the structure of the retina changes from a bent form to a linear isomer. This isomerization of retinal activates rhodopsin, triggering a series of processes that culminate in the closure of sodium channels in the photoreceptor membrane. Visual receptors, in contrast to most other sensory neurons, become hyperpolarized and forced away from the threshold when exposed to a stimulus (Lumen) (n.d.-b).

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The retina of the eye receives and reacts to incoming light, sending messages to the brain that allow one to see. The eye’s so-called blind spot is a portion of the retina that does not provide visual information. The photoreceptors are located at the rear of the retina, the ganglion cells are located at the front, and the ganglion cell axons make up the optic nerve, which exits through a hole in the back. The photoreceptors are responsible for converting light energy into a neurological signal. When photoreceptors are absent, there is no responsiveness to light.
9. Light passes through the cornea and lens, combining to generate a crisp image of the visual world on the retina, which is a sheet of photoreceptors. The image on the retina is reversed, just like in a camera: objects above the center project to the lower part, and vice versa. The information from the retina is transferred to other areas of the brain via the optic nerve in the form of electrical signals, which are then processed to allow humans to see. As a result, the visual process starts with a comparison of the amount of light striking each small part of the retina to the amount of light surrounding it. The lateral geniculate nucleus of the thalamus relays visual information from the retina to the main visual cortex. This is a tiny strip of tissue that is less than one-tenth of an inch thick and is found in the back of the brain’s occipital lobe. The brain’s occipital lobe is located at the rear of the head (Society for Neuroscience, 2016).
The main visual cortex, like the retina, is densely packed with cells in many layers. Scientists discovered responses in its intermediate layer, which receives messages from the lateral geniculate nucleus. These responses are identical to those seen in the retina and lateral geniculate cells. Above and below this layer, cells react differently. They favor stimuli in the form of bars or edges, as well as those that are oriented in a specific way. Further research has revealed that various cells prefer edges that are at different angles or that move in a specific direction. Even though the mechanics of visual perception are still unknown, latest discoveries from anatomical and physiological research in primates reveal that visual signals are passed into at least three different processing systems. One system appears to process information primarily about shape; another appears to process information primarily about color; and a third seems to process information primarily about mobility, position, and spatial distribution (Society for Neuroscience, 2016). Situations that can impede visual information in the brain are those that affect light entering the eye and those that affect the brain. Examples are glaucoma and a road traffic accident affecting the occipital region.
10. The words ‘visual attention’ refer to a set of cognitive operations that mediate the selection of relevant and the filtering out of irrelevant information from cluttered visual scenes. In everyday life, visual scenes typically contain more items than can be processed at any one time due to the limited processing capacity of the visual system. Visual attention refers to the cognitive operations that allow us to efficiently deal with this capacity problem by selecting relevant information and by filtering out irrelevant information. Attention is a highly flexible mechanism that can operate on regions of space, particular features of an object, or on entire objects. Attention can also be directed either overtly or covertly. For instance, if a barking dog ran up to you, you would not only direct your attention towards it, but would also look directly at it, deploying overt attention (McMains & Kastner, 2020).
The five filtering techniques are spotlight, zoom-lens, selective auditory, attenuation, and spatial filtration. The similarities include neurobiological adaptations using the same neuronal pathways, while the differences encompass the modality of visual adaptation by each technique. The examples respectively are the effects of a spotlight on the brain, decreasing or increasing the size of focus, subconcious shutting out of auditory stimuli, limiting the effects of a sensory input such as noise, and selectively albeit subconsciously filtering sensory input in relation to spatial origin (McMains & Kastner, 2020).  Mid-Term Essay Exam Essay Example

References
AlleyDog.com (2021). Herman Ludwig Ferdinand Von Helmholtz: Unconscious inference. https://www.alleydog.com/glossary/definition.php?term=Herman+Ludwig+Ferdinand+Von+Helmholtz
Delahunt, P.B. & Brainard, D.H. (2004). Color constancy under changes in reflected illumination. Journal of Vision, 4(9). https://doi.org/10.1167/4.9.8
Kelber, A., Yovanovich, C., & Olsson, P. (2017). Thresholds and noise limitations of color vision in dim light. Philosophical Transactions of the Royal Society B, 372(1717). https://doi.org/10.1098/rstb.2016.0065
Lumen (n.d-a.). Introduction to psychology: Sensation and perception. https://askinglot.com/goto/139624A9
Lumen (n.d.-b). Vision. Boundless Biology. https://courses.lumenlearning.com/boundless-biology/chapter/vision/
McMains, S.A., & Kastner, S. (2020). Visual Attention. Encyclopedia of Neuroscience, 318-324. https://doi.org/10.1007/978-3-540-29678-2_6344
National Eye Institute [NEI] (2019). How the eyes work. https://www.nei.nih.gov/learn-about-eye-health/healthy-vision/how-eyes-work
Schultz, H. (2017). You know what they say about assuming: The likelihood principle and unconscious inference. https://onlyhuman2.swanpsych.com/2017/12/01/you-know-what-they-say-about-assuming-the-likelihood-principle-and-unconscious-inference/
Society for Neuroscience (2016). Vision : Processing information. https://www.brainfacts.org/thinking-sensing-and-behaving/vision/2012/vision-processing-information
Tortora, G.R. & Derrickson, B. (2014). Principles of anatomy and physiology, 14th ed. John Wiley & Sons, Inc.
UCAR (2018). Visible light. Center for Science Education. https://scied.ucar.edu/learning-zone/atmosphere/visible-light
Webster, M.A. (2012). Evolving concepts of sensory adaptation. F1000 Biology Reports, 4(21). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3501690/ Mid-Term Essay Exam Essay Example