Examples of Feature Same-Different Displays

Texture Displays | Feature Displays | Geometric Displays | Object Displays

Examples of Feature Stimulus Displays

The feature display type was similar overall to the texture display type in its general organization. That is, the Different displays of this type contained an odd contrasting Atarget@ region in either color or shape that did not exist in the Same displays. Further inspection of the displays below, however, will reveal the interesting challenge of this display type. A critical difference between the texture and feature display types was the presence of local irrelevant variation in the latter, such that the identity of the local elements forming the globally contrasting target and distractor regions of this display type varied at random with these regions. As a result, the birds could only discriminate the presence or absence of the odd target region based on a global evaluation of the display=s overall structure, and not merely the presence and absence of local differences. For instance, in the examples of the Same displays, the birds would need to ignore the irrelevant variation in the display and respond instead to the global sameness of the repeated shape or color over the entire display in order to make an accurate choice. Thus, unlike Cook et al.=s (1995) pigeons, the present birds did not have the option of discriminating the displays based on only a local examination of the color and shape elements in the displays.