These results are not consistent with the hypothesis that the crows built a mental scenario, either during their successful solution of the standard string-pulling problem or after the first pull-step on the visually-restricted apparatus.
The 'insight' hypothesis assumes that the string-pulling problem is mentally solved by an animal either before interaction or after the first pull-step has been completed [8].
Determining if the meat had moved closer would have been most difficult after the first pull-step as crows would need to judge from a relatively long distance whether the meat had moved a few centimetres towards them or not.
Nevertheless, even after the first pull-step on the visually-restricted apparatus, the crows experienced at standard string pulling showed a drop in performance and an increase in error rates.
This difference supports the hypothesis that side-on visual feedback via the mirror allowed crows to detect if the meat moved closer after the first pull-step and so reinforced these actions.
Compared to standard string pulling, after the first pull-step the experienced group made 10 times as many errors (One-tailed Wilcoxon signed-ranks test: Z = 10, p = 0.0625) and their mean pull-step ratio dropped from 96.5±1.86% to 55.7±10.1% (One-tailed Wilcoxon signed-ranks test: Z = −10, p = 0.0625).
After the first pull-down, immunoprecipitated material was recovered with 10 mM dithiothreitol in immunoprecipitation buffer at 37°C for 30 minutes, diluted and subjected to a second round of immunoprecipitation.
However, after the second pull-step he pulled without stepping then left the apparatus.
And Reddick, who had struck out in his first three at-bats and flung his bat and helmet toward the dugout after fanning in the third, pulled a tiebreaking home run to right.
