MCAT Social and Behavioral Sciences › Principles of Sensation
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 also test whether reading fluency in the three conditions varied by language status (i.e., native English speaker vs. participants who learned English as a second language later in life). Whereas in the original study, participants in conditions one and two did not vary significantly in reading fluency, participants who learned English as a second language later in life were slower at reading the sentences in condition two compared to condition one. Given this effect, the researchers would be most likely to conclude which of the following?
Native English speakers rely more heavily on top-down processing whereas individuals who learned English as a second language later in life rely more on bottom-up processing in reading.
Native English speakers rely more heavily on bottom-up processing whereas individuals who learned English as a second language later in life rely more on top-down processing in reading.
Individuals who learned English as a second language later are more likely to have reading disorders.
Native English speakers are less likely to use a-priori knowledge of the English language to form fast mental impressions of words.
Native English speakers would probably have much more exposure to English words from a young age; therefore, they have more a-priori knowledge (i.e. a top-down approach) of the features of English words compared to non-native speakers who probably rely more on the decoding of individual letters to form a word (i.e. a bottom-up approach). Even though fluency was poorer in condition two for non-native speakers, this does not mean that they have a reading disorder.
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?
Loudness
Pitch
Quality/purity
Instrumentation
In the passage, amplitude refers to loudness. On the other hand, frequency refers to pitch while timbre refers to quality/purity of sound.
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 also test whether reading fluency in the three conditions varied by language status (i.e., native English speaker vs. participants who learned English as a second language later in life). Whereas in the original study, participants in conditions one and two did not vary significantly in reading fluency, participants who learned English as a second language later in life were slower at reading the sentences in condition two compared to condition one. Given this effect, the researchers would be most likely to conclude which of the following?
Native English speakers rely more heavily on top-down processing whereas individuals who learned English as a second language later in life rely more on bottom-up processing in reading.
Native English speakers rely more heavily on bottom-up processing whereas individuals who learned English as a second language later in life rely more on top-down processing in reading.
Individuals who learned English as a second language later are more likely to have reading disorders.
Native English speakers are less likely to use a-priori knowledge of the English language to form fast mental impressions of words.
Native English speakers would probably have much more exposure to English words from a young age; therefore, they have more a-priori knowledge (i.e. a top-down approach) of the features of English words compared to non-native speakers who probably rely more on the decoding of individual letters to form a word (i.e. a bottom-up approach). Even though fluency was poorer in condition two for non-native speakers, this does not mean that they have a reading disorder.
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?
Loudness
Pitch
Quality/purity
Instrumentation
In the passage, amplitude refers to loudness. On the other hand, frequency refers to pitch while timbre refers to quality/purity of sound.
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
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.
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
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.
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 firfty percent of the time
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
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.
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 firfty percent of the time
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
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.
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 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 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 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.
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?
Weber
Durkheim
Cooley
Mead
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.