Which one of the following is most analogous to the manner in which fMRI scans of brain activity are typically interp...

Jeremy on May 25, 2019

Could you please explain why D is incorrect?

I understand why B is the correct answer, but could you please walk me through why D is an invalid answer choice? Thank you.

2 Replies

Victoria on May 25, 2019

Hello @JeremyG,

The passage tells us that fMRI scans are typically interpreted by subtracting the baseline measurement of metabolic activity from the on-task measurement. The remaining areas of the brain that are lit up by the fMRI are interpreted to be those that are associated solely with the cognitive task in question.

B is the correct answer as it 'subtracts' the increase in summer shoppers from the yearlong advertising campaign and uses this information to conclude that the summer shoppers were the only shoppers that were affected by the yearlong campaign as they were the only ones remaining following this 'subtraction.'

D is incorrect because it is based on an assumption made using information that we are not provided with. We cannot 'subtract' office Internet use from home Internet use or vice versa and we are not provided with an overall picture of Internet use throughout the day. In addition, the fMRI interpretation concludes that what remains is only associated with the task whereas answer choice D concludes that most of the Internet traffic comes from homes rather than the Internet traffic only coming from homes.

Hope this is helpful! Please let us know if you have any further questions.

Jeremy on May 25, 2019

That clears it up, thanks!