# MCAT Social and Behavioral Sciences : Principles of Sensation

## Example Questions

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### Example Question #1 : Sensory Threshold And Weber's Law

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 for the low amplitude condition, increasing the amplitude by ten decibels resulted in participants noticing a difference half of the time (the other half of the time, they did not detect a difference between the two stimuli). The researchers can make which of the following conclusions?

The researchers cannot conclude that they identified the just-noticeable difference for the low condition because just-noticeable difference is defined as the amount by which a stimulus needs to change for a human to perceive a difference 100% of the time.

The researchers can conclude that they identified the just-noticeable difference for the low condition because just-noticeable difference is defined as the amount by which a stimulus needs to change for a human to perceive a difference at least 50% of the time.

The researchers can conclude that they identified the just-noticeable difference for the low condition because just-noticeable difference is defined as the amount by which a stimulus needs to change for a human to perceive a difference at least 25% of the time.

The researchers cannot conclude that they identified the just-noticeable difference for the low condition because just-noticeable difference is defined as the amount by which a stimulus needs to change for a human to perceive a difference at least 75% of the time.

The researchers can conclude that they identified the just-noticeable difference for the low condition because just-noticeable difference is defined as the amount by which a stimulus needs to change for a human to perceive a difference at least 50% of the time.

Explanation:

The just-noticeable difference is the amount that the stimulus needs to change in order for a human to perceive a difference half of the time or more. In this case, participants in the low amplitude condition were able to identify a difference half of the time when the amplitude was increased by ten decibels.

### Example Question #161 : Mcat Social And Behavioral

Excerpt from “Two Kinds of Vocational Education” by Julius T. House, 1921

American Journal of Sociology, Vol. 27, No. 2 (Sep., 1921), pp. 222-225

There are two schools of thinkers interested in vocational education. One of these is individualistic, thinks in teams of fitting the child to the job, accepts the present economic system with little, if any, criticism. It would isolate consideration of the vocation, so far as possible, from consideration of its social purposes. Psychologically its plan is based upon habit, with no thought of developing in the child a sense of the relation of his work to the whole social process. To secure the result sought there must be early separation of technical schools from the rest of the school system. It is proposed to begin with the seventh grade, the so-called junior high school.

The purpose of the technical school is and will be to get the answer, already known to the teacher, by the shortest route. Emphasis will be laid on rapid calculation; swift, effective movement; automatic response. The typewriter, the shorthand notebook, the hammer and nail, the stove, the furnace, the retort, are the instruments of education. A technique of salesmanship and advertising, without the regard to the ethics of these operations and with no comprehension of the principles of psychology, is developed. Rough-and-ready adaptation to a rough-and-ready business world is the goal.

Certain results follow: (1) Even more rigid division of industrial life between two groups: those who manage, in whom power of initiative is vested; those who are skilled in narrow processes with no outlook upon the meaning of the work. (2) The exploitation of this isolated class. (3) The establishment of an institution to perpetuate this condition. Custom is already being instituted of sending the children of poor families to this manual-skill-producing school. (4) Public taxation to support institutions to assist business based on the supposition that when business prospers moral values take care of themselves.

The second group of thinkers, seemingly few but with men like John Dewey leading, are interested in vocational education as a means of introducing the child more intimately into the life of society. It is believed that such study should be directed to the perception of the relation of vocations to all the social process. Therefore all the students are to study all the vocations. The choice of a life-work will be, then, only a by-product of the training—important indeed, but still a by-product. Already such work is done in the grades. It remains only to enlarge it and relate it to the proper sciences as the later years of school life are reached.

The author argues that the working class will be continually exploited by the managing class. Suppose that one manager slowly decreases the hourly wage of his employees by $0.03 every month. The workers are bothered, but don’t feel that it effects them that much. Another manager outrages his employees by dropping the hourly wage by$0.40. Who developed a law of sensory perception that accurately models this scenario?

Durkheim

Cooley

Weber

Weber

Explanation:

Max Weber developed the Weber’s law of sensory perception while studying human stimulus. This law  describes how a change in perception is proportional to the starting stimulus. For example, if a person holding a 50 pound weight cannot feel anything less than five pounds being added, then a person holding 100 pounds will not be able to feel anything less than 10 pounds being added. For the wage examples, one group was not disturbed because the amount of change was below their threshold of importance.

### Example Question #161 : Mcat Social And Behavioral

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.

Imagine that this study used a forced choice design in which participants had to select "the same" or "different" after hearing a pair of sounds at different amplitudes. As the amplitude of the comparison sound increased, which type of signal detection response would be most likely, regardless of the initial sound?

False alarm

Correct rejection

Miss

Hit

Hit

Explanation:

In forced-choice signal detection method, responses can be classified into four categories: miss (failing to identify a changed stimulus), false alarm (identifying an unchanged stimulus as changed), correct rejection (identifying an unchanged comparison as the same as the initial stimulus), or hit (correctly identifying a comparison stimulus that differs from the initial stimulus). As the amplitude is increased, it is also more likely that the subject would be able to correctly identify a changed stimulus. The greater the discrepancy in magnitude for the two sounds, the more likely the participant will get a hit.

### Example Question #1 : Principles Of Sensation

Which of the following is an example of sensory adaptation?

Music at a concert seems less loud at the end of the night

Being able to see a candle flame at thirty miles on a dark clear night

Needing more of a drug to feel its effects after taking it for a while

None of these

Music at a concert seems less loud at the end of the night

Explanation:

Sensory adaptation is the gradual alteration in sensitivity with prolonged stimulation or the absence of stimulation. Being able to see the candle flame is an example of "absolute threshold," which is the minimum intensity of a stimulus for humans to be able to detect the stimulus fifty percent of the time. Last, needing more of a drug to feel its effects is an example of tolerance.

### Example Question #1 : Detection Theory And Sensory Adaptation

What is the definition of a "just-noticeable difference"?

The amount by which a stimulus needs to change for a human to perceive a difference at least twenty-five percent of the time

The amount by which a stimulus needs to change for a human to perceive a difference at least sventy-five percent of the time

The amount by which a stimulus needs to change for a human to perceive a difference all of the time

The amount by which a stimulus needs to change for a human to perceive a difference at least firfty percent of the time

The amount by which a stimulus needs to change for a human to perceive a difference at least firfty percent of the time

Explanation:

Just-noticeable difference (JND) is the amount that a stimulus needs to change for someone to be able to notice it at least half the time. For example, the JND needed to perceive that a light is brighter is a two percent change in the brightness of the light’s illumination. This means that when the brightness goes up by two percent, we would be able to notice a difference half of the time or more.

### Example Question #161 : Mcat Social And Behavioral

As a part of a research study, Carlos was presented with a sound. He was instructed to press "S" (for “same”) every time that he heard the same sound, and to press "D" (for “different”) every time he heard a different sound. At the end of the test, Carlos was informed that he correctly pressed "S" for every same sound, but incorrectly identified many of the different sounds as “same sounds.” Carlos' ability to detect signals would be described as which of the following?

None of these

Excellent selectivity, but poor sensitivity

Excellent sensitivity, but poor selectivity

Equal sensitivity and selectivity

Excellent sensitivity, but poor selectivity

Explanation:

Sensitivity is the ability to detect a true signal. Carlos correctly identified all of the "S" sounds; however, he missed many of the "D" sounds, indicating that his selectivity is poor. In medicine, doctors desire that screening instruments (e.g. mammograms as a screening for breast cancer) have high sensitivity so that no cases or symptoms are missed. Selectivity is less important for screening.

### Example Question #1 : Principles Of Sensation

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.

Which of the following choices best describes amplitude?

Quality/purity

Instrumentation

Loudness

Pitch

Loudness

Explanation:

In the passage, amplitude refers to loudness. On the other hand, frequency refers to pitch while timbre refers to quality/purity of sound.

### Example Question #1 : Perceptual Concepts And Organization

Perception is the process that occurs when the brain processes sensory stimuli and translates them in a way that a person can understand. Perception is not usually a conscious process; furthermore, sensing a particular stimulus is a different process than the interpretation (i.e. perception) of that stimulus.

A team of perception researchers decided to test the difference between sensation and perception by testing the reading speed of a paragraph in three conditions. In the first condition, the researchers correctly spelled the words in the sentences. In the second condition, they had the same words with the letters randomly jumbled within each word; however, the first and last letter of each word remained in the correct position. In the third condition, researchers used the same words and randomly jumbled every letter in each word, including the first and last letters. Sample sentences from the paragraphs are below:

1). Mary crossed the street to purchase a cookie after lunch.

2). Mray csorsed the sretet to pruachse a ckooie atfer lnuch.

3). Rmya rsocsed het teerst to curaepshs a okocei feart culhn.

The researchers timed how long it took for the participants to correctly say a sentence fluently. They found that participants in condition three took significantly more time to read the sentence fluently, whereas they found no significant difference in the average amount of time it took participants to read the passage in condition one compared to condition two.

Suppose the researchers were also interested in the amount of time it took the participants in each condition to read each letter fluently (as opposed to each word). In order to test this phenomenon, participants across conditions were instructed to read each letter aloud as quickly and as correctly as possible. They found no group differences in letter reading speed or accuracy. Based on these results, the researchers would most likely conclude which of the following?

For reading, perceptual processes involve more than decoding individual letters.

All of these

For reading, top-down processes are more often used than bottom-up processes.

It is unlikely that participants in condition three were reading the words more slowly in the initial experiment due to poor reading ability.

All of these

Explanation:

If participants in all three conditions did not differ in letter reading speed, but they differed in word reading speed, then it suggests that reading is not just decoding letters. In other words, top-down processes are at play. In a top-down process, the brain uses a-priori knowledge of the world to form percepts or mental impressions about what a stimulus might be.

Given that participants in condition three were reading slower, it could be that their reading ability was poorer to begin with (i.e. a confounding variable); however, because they can read letters just as fluently as the other groups, it is unlikely that the groups differ in reading ability.

### Example Question #1 : Other Senses And Sensation Principles

Perception is the process that occurs when the brain processes sensory stimuli and translates them in a way that a person can understand. Perception is not usually a conscious process; furthermore, sensing a particular stimulus is a different process than the interpretation (i.e. perception) of that stimulus.

A team of perception researchers decided to test the difference between sensation and perception by testing the reading speed of a paragraph in three conditions. In the first condition, the researchers correctly spelled the words in the sentences. In the second condition, they had the same words with the letters randomly jumbled within each word; however, the first and last letter of each word remained in the correct position. In the third condition, researchers used the same words and randomly jumbled every letter in each word, including the first and last letters. Sample sentences from the paragraphs are below:

1). Mary crossed the street to purchase a cookie after lunch.

2). Mray csorsed the sretet to pruachse a ckooie atfer lnuch.

3). Rmya rsocsed het teerst to curaepshs a okocei feart culhn.

The researchers timed how long it took for the participants to correctly say a sentence fluently. They found that participants in condition three took significantly more time to read the sentence fluently, whereas they found no significant difference in the average amount of time it took participants to read the passage in condition one compared to condition two.

The observation that participants did not differ in reading time between conditions one and two illustrates that humans rely on which of the following principles when reading?

Bottom-up processing

Inattentional blindness

Phi phenomenon

Top-down processing

Top-down processing

Explanation:

Top-down and bottom-up processing are both examples of feature analysis, which allows us to detect specific elements and assemble them into a more complex visual form. A top-down process is a progression from the whole to the details (in this case, from the whole word to the individual letters). Bottom-up processing is the opposite; it is the progression from individual elements to the whole. Because participants in condition two were still reading as quickly as those in condition one, it suggests that in reading, humans process the whole word rather than each individual letter (i.e. top-down process).

The Phi Phenomenon is the illusion of movement created by presenting visual stimuli in rapid succession (e.g. a cartoon flip book). Inattentional blindness occurs when someone is hyper-focused on one stimulus and unable to take in other information.

### Example Question #11 : Other Senses And Sensation Principles

Perception is the process that occurs when the brain processes sensory stimuli and translates them in a way that a person can understand. Perception is not usually a conscious process; furthermore, sensing a particular stimulus is a different process than the interpretation (i.e. perception) of that stimulus.

A team of perception researchers decided to test the difference between sensation and perception by testing the reading speed of a paragraph in three conditions. In the first condition, the researchers correctly spelled the words in the sentences. In the second condition, they had the same words with the letters randomly jumbled within each word; however, the first and last letter of each word remained in the correct position. In the third condition, researchers used the same words and randomly jumbled every letter in each word, including the first and last letters. Sample sentences from the paragraphs are below:

1). Mary crossed the street to purchase a cookie after lunch.

2). Mray csorsed the sretet to pruachse a ckooie atfer lnuch.

3). Rmya rsocsed het teerst to curaepshs a okocei feart culhn.

The researchers timed how long it took for the participants to correctly say a sentence fluently. They found that participants in condition three took significantly more time to read the sentence fluently, whereas they found no significant difference in the average amount of time it took participants to read the passage in condition one compared to condition two.

Suppose the researchers wanted to test the Gestalt principle of proximity. In order to do this, they might consider which of the following options?

Test if varying the size of the words impacted reading fluency.

Test if varying the amount of space between words impacted reading fluency.

Test if varying the color of words impacted reading fluency.

Test if varying the font of words impacted reading fluency.