Space-based, object-based, and the grouped array theories of attention were examined using modified versions of Watson and Kramer's target judgment task. In addition, I examined how predictions from the three theories can be used in an applied context (i.e. the design of traffic signs).

There were six experiments. Experiment 1A examined the effects of spatial precuing and spatial separation on judgments for a target judgment task and found no significant results. On Experiment 1B, the precue was modified into a go/no go task. The results of Experiment 1B indicated a precue benefit. Also, the results indicated a benefit in performance for different-object judgments at large spatial separations. Experiment 2 compared between-object and within-object precues and found a different object benefit. Experiment 3 was conducted to examine whether preattentive processing is dependent on modal completion. Comparisons were made between different sign configurations (UCR object, an amodal object, and a grouped object). The results indicated a different object benefit for the UCR sign and amodal sign. However, when the wrenches were presented on the grouped unit sign, subjects had higher accuracy for features presented on the same wrench. Experiment 4 was conducted to examine the how the connectedness of an object's representation and top down information affected performance on an object judgment task. The results indicated faster speed responses for valid precues. However, for invalid precues, responses were significantly slower for occluded as compared to continuous wrenches. This result supported the UCR object theory that a perceptual object is formed when uniform connected regions are present. Experiment 5 examined whether the connectedness of a sign affected perceptual processing in a real world setting. Symbols from traffic signs were used in three different sign configurations (continuous region, connected region, and separate regions). Subjects were faster to respond to targets located on the same as compared to different continuous regions for the connected region sign. The connected sign was processed as two separate objects rather than a single continuous object. Similar to the results of Experiment 1B, there was an advantage for making comparisons between objects rather than within a single object.