Source: Revised GRE PDF 2nd Ed. Section 3; #21 (p. 59)

2

The passage asserts which of the following

The decrease in responsiveness that follows continuous stimulation (adaptation) is common to all sensory systems, including olfaction. With continued exposure to chronically present ambient odors, individuals’ perception of odor intensity is greatly reduced. Moreover, these perceptual changes can be profound and durable. It is commonly reported that following extended absences from the odorous environment, reexposure may still fail to elicit perception at the original intensity. Most research on olfactory adaptation examines relatively transient changes in stimulus detection or perceived intensity—rarely exceeding several hours and often less—but because olfactory adaptation can be produced with relatively short exposures, these durations are sufficient for investigating many parameters of the phenomenon. However, exposures to odors in natural environments often occur over far longer periods, and the resulting adaptations may differ qualitatively from short-term olfactory adaptation. For example, studies show that even brief periods of odorant stimulation produce transient reductions in receptors in the olfactory epithelium, a process termed “receptor fatigue.” Prolonged odor stimulation, however, could produce more long-lasting reductions in response, possibly involving structures higher in the central nervous system pathway. The passage asserts which of the following about the exposures involved in the “research on olfactory adaptation” (line 11)? The exposures are of long enough duration for researchers to investigate many aspects of olfactory adaptation., The exposures have rarely consisted of reexposures following extended absences from the odorous environment., The exposures are intended to reproduce the relatively transient olfactory changes typical of exposures to odors in natural environments., Those exposures of relatively short duration are often insufficient to produce the phenomenon of receptor fatigue in study subjects., Those exposures lasting several hours produce reductions in receptors in the olfactory epithelium that are similar to the reductions caused by prolonged odor stimulation.

2 Explanations

1

jahnavi jha

Can you kindly explain why is "C" wrong as it tells as that the study is intending to produce effects typical of what is seen in natural environment.

Aug 26, 2018 • Comment

Sam Kinsman, Magoosh Tutor

Hi Jahnavi,

Let's take a look at part of the passage:

"Most research on olfactory adaptation examines relatively transient changes in stimulus detection or perceived intensity—rarely exceeding several hours and often less (.....). However, exposures to odors in natural environments often occur over far longer periods, and the resulting adaptations may differ qualitatively from short-term olfactory adaptation."

Ok, so we are told that when research is done on olfactory adaptation, it looks at changes that take place over a few hours. And we are told that in natural environments, exposures to odors happen over much longer periods.

Therefore, the exposures to odors that take place in a research setting are not really trying to "reproduce the relatively transient olfactory changes typical of exposures to odors in natural environments." That's because in natural environments, it's not typical (or common) to have olfactory changes over short periods of time. It's more typical to have changes over long periods of time (for example, a person who lives by the sea gets used to the salty smell of the sea).

Aug 29, 2018 • Reply

2

Gravatar Chris Lele, Magoosh Tutor

Sep 21, 2012 • Comment

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