MCAT Social and Behavioral Sciences : Processing and Integrating Visual Signals

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Example Questions

Example Question #1 : Processing And Integrating Visual Signals

Myopia is a very common condition. What is myopia and which type of lens can correct it?

Possible Answers:

Farsightedness; concave (i.e. diverging) lens

Farsightedness; convex (i.e. converging) lens

Nearsightedness; concave (i.e. diverging) lens

None of these

Nearsightedness; convex (i.e. converging) lens

Correct answer:

Nearsightedness; concave (i.e. diverging) lens

Explanation:

Myopia is nearsightedness, meaning the focal length is too short. This can be caused by too much refraction at the eye's lens or if the eyeball is too long. Myopia can be corrected using a concave (i.e. diverging) lens, which will increase the focal length as shown in the figure. 

Myopia diagram

Example Question #2 : Processing And Integrating Visual Signals

Signal detection studies measure an individual’s ability to detect certain stimuli. They involve exposure to stimuli at varying magnitudes and ask subjects to detect any changes in their perceptual experience of the stimuli (i.e. the just-noticeable difference). Perceiving magnitude differences in stimuli depends on the type of sensory experience (e.g. touch or sound) and is based on proportional rather than absolute amounts. 

Imagine a hypothetical study that asked participants to perceive changes in amplitude of a sound stimulus. In this experiment, the researchers wanted to know how much the amplitude needed to change in order for an individual to detect a difference. They decided to test the just-noticeable difference at three different amplitudes: low, medium, and high. Participants in each category listened to the initial sound, and then the amplitude was increased or decreased slightly until participants detected a difference. 

The researchers found that the absolute difference in amplitude that needed to occur in order for participants to detect a difference varied by condition (i.e. low, medium, high amplitude). This observation best illustrates which of the following? 

Possible Answers:

Weber's law because the just-noticeable difference necessary to detect a change in the magnitude of a comparison stimulus (i.e., the amplitude) is a constant proportion of the initial stimulus. 

Sensory adaptation because as the body is continually exposed to a stimulus, the nerve receptors fire more frequently. 

Sensory adaptation because as the body is continually exposed to a stimulus, the nerve receptors fire less frequently. 

Weber's law because the just-noticeable difference necessary to detect a change in the magnitude of a comparison stimulus is always half the magnitude of the initial stimulus. 

Correct answer:

Weber's law because the just-noticeable difference necessary to detect a change in the magnitude of a comparison stimulus (i.e., the amplitude) is a constant proportion of the initial stimulus. 

Explanation:

Weber's law states that the change in a stimulus that will be just noticeable is a constant ratio of the original stimulus. Because the original stimulus changes in each condition (i.e. low, medium, high), the ratio for the just-noticeable difference also changes; therefore, the magnitude necessary to detect a change will vary by condition. 

Example Question #3 : Processing And Integrating Visual Signals

Approximately what percent of the total sensory receptors of the body are in the eyes?

Possible Answers:

Correct answer:

Explanation:

The eyes contain approximately seventy percent of the total sensory receptors of the body. Most of these are located in the retina, which has up to 200,000 photoreceptor cells per square millimeter in its densest location (i.e. the fovea centralis).

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