Ornithologists conditioned a flock of starlings to associate a series

Question

Ornithologists conditioned a flock of starlings to associate a series of musical soft chirps with the presence of a housecat. One and two days later, the ornithologists conducted tested the starlings, both individually and as a flock, to ascertain whether the birds retained the conditioning. Individually, the birds were significantly less likely to avoid areas where the soft chirps were being played. The ornithologists hypothesized that when the chirps were played, a starling that retained the conditioned association sounds an alarm that arouses the attention of the rest of the flock, retriggering the association in them and thereby making them avoid the sound.

The ornithologists' hypothesis requires which of the following assumptions?

A. The starlings do not produce soft chirps as alarm signals.
B. Before they were conditioned, the starlings would likely have found the chirps used in the experiment to be pleasant.
C. Starlings that did not avoid the musical soft chirps when tested individually were less likely than the other starlings to avoid the chirps when tested in a group.
D. Starlings that did not avoid the musical soft chirps when tested individually were not merely following other starlings' movements when tested in a flock.
E. A housecat was used during both the starlings' conditioning and the subsequent tests.

wang3022 · Answer

Why is it not B? Why is D correct?

Matty101 · Answer

B  suggests that the starlings must have found the chirping pleasant at some point prior to the conditioning. However, that is not a necessary condition for the assumption to hold. The starlings might have been neutral toward the chirping; nothing requires them to have found it pleasant for the assumption to be valid.

D  is correct, because the stimulus suggests the starlings are reacting to an alert sent out by one of their own, that allows the to ignites their past conditioning responses. However, if the starlings are just reacting to the movements of another starlings movement rather than a dedicated alert, that reminds them of their past conditioning, then it would have not have anything to do with the alert reigniting the conditioned response. Rather it would just be following what other birds do.

Bunuel · Answer

Experts' Global Explanation:   
 
Mind-map:  Starlings conditioned to associate musical chirps with a housecat à testing to determine retention of conditioning à starlings avoided musical chirps more in flock than individually à a starling retaining the conditioning gives off an alarm to other starlings for them to avoid musical soft chirps (conclusion)

Missing-link:  Between starlings avoiding musical chirps more in flock than individually and the conclusion that a starling retaining the conditioning gives off an alarm to other starlings for them to avoid musical soft chirps

Expectation from the correct answer choice:  To strengthen the conclusion that a starling retaining the conditioning gives off an alarm to other starlings for them to avoid musical soft chirps, through a valid assumption

A. The argument is concerned with a starling giving off an alarm to other starlings, and   not with the nature of the alarm  ; so, this answer choice simply adds detail and has no bearing on the reasoning or its conclusion. Besides, this condition   is not necessary for the argument to hold   and thus, is not a valid assumption. Because this answer choice does not strengthen the conclusion through a valid assumption, this answer choice is incorrect.

B. Whether the starlings would likely have found the chirps used in the experiment to be pleasant has   no bearing on the argument   or its conclusion. Besides, this condition   is not necessary for the argument to hold   and thus, is not a valid assumption. Because this answer choice does not strengthen the conclusion through a valid assumption, this answer choice is incorrect.

C. Trap. By suggesting that the starlings that did not retain the conditioning were “less likely than others” to avoid musical chirps in a flock, this answer choice   contradicts the argument’s suggestion   that once a starling gives off an alarm to other starlings, all starlings were “equally likely” to avoid musical chirps (and more likely than they would be in individual testing). Because this answer choice does not strengthen the conclusion through a valid assumption, this answer choice is incorrect.

D.  Correct . By suggesting that the starlings that did not retain the conditioning   were not merely following other starlings’ movements in a group test  , this answer choice   strengthens the conclusion   that, in a flock, a starling retaining the conditioning gives off an alarm to other starlings for them to avoid musical soft chirps. Additionally, this statement   does have to be true   for the conclusion to hold; negating this statement would mean that “starlings that did not avoid the musical soft chirps when tested individually were merely following other starlings' movements when tested in a flock”; such a suggestion casts doubt on one starling giving off an alarm to other starlings and thus, negates the conclusion. Because this answer choice strengthens the conclusion through a valid assumption, this answer choice is correct.

E. The use of a housecat in the later tests   casts doubt   regarding   whether it was the housecat or the alarm by a fellow starling that made the starlings avoid musical chirps   in a flock test; so, this answer choice, if anything,   weakens, rather than strengthens  , the argument. Because this answer choice does not strengthen the conclusion through a valid assumption, this answer choice is incorrect.

D is the best choice.

Ornithologists conditioned a flock of starlings to associate a series

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Critical Reasoning (CR) Questions

Ornithologists conditioned a flock of starlings to associate a series

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards