DescriptionAmerican Journal of Psychology (Volume 21) Fig 5.jpg English: The same female English Sparrow using the beak in addition to her claws. The door...
DescriptionAmerican Journal of Psychology (Volume 21) Fig 6.jpg English: The female English Sparrow of Figs. 1-5. Strings now changed to Place 2. She...
DescriptionAmerican Journal of Psychology (Volume 21) Fig 23.jpg English: Young Crow 1 shown opening the door by pulling String C in Place 5. The Old Crow...
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