Reference no: EM133403993

Case Study: A "spotlight" is a metaphor that nicely captures many characteristics of the focus of visual attention: It is a "beam" that is moved spatially, that may not be divided, and that enhances the detection of events falling within it.

Some of the strongest evidence supporting the unitary concept of attention comes from the luminance-detection paradigm (e.g., Posner, 1980). In such experiments, participants are first cued with the likely spatial location of a target and then respond as rapidly as possible when the target appears at any location in the display. For example, in a typical display, the stimuli are arranged horizontally with a fixation point in the center, which is also the location where the cue appears. The cue is either valid, correctly identifying the spatial location of the target, or invalid, incorrectly identifying the location of the target. Following the presentation of the cue, a single target stimulus is illuminated (usually about 1000 ms after the onset of the cue) and participants respond as soon as they detect the target, regardless of its location. Relative to a neutral cue condition, responses are faster when the target appears in the cued location (a valid trial) and slower when the target appears in a non-cued location (an invalid trial).

Demonstrations of these patterns of results occur independently of eye movements. In other words, when an eye tracker verifies that your eyes are still fixed on the center, your focus of attention can be off to the right, or off to the left. While other interpretations of these findings are possible, they are consistent with the notion of a focused beam of attention that may be moved to distinct spatial locations - incorrectly in the case of the an invalid trial and correctly in the case of a valid trial.

Question 1. In the CogLab experiment did we use a central (endogenous) cue or a peripheral (exogenous) cue? Provide a new example of a central cue and a new example of a peripheral cue (for each, tell me what the cue is and where it would be presented).

Question  2. If the interval between the cue and the target were 200 ms, which type of cue (central or peripheral) would likely produce larger costs and benefits? If the interval between the cue and the target were 800 ms, which type of cue (central or peripheral) would produce larger costs and benefits? Explain why this pattern makes sense given the nature of the cues.

Question 3. In our experiment the cue predicted the location of the target correctly on the majority of trials (80% correct) and you were told that at the start of experiment. Suppose that, instead, we created an experiment where the cue was random and uninformative (i.e., correctly predicted the location of the target on half of the trials and incorrectly predicted the location of the target on half of the trials), and we told the participant that the cue would be random. What do you think the pattern of results would look like under these conditions if the cue were central? What do you think the pattern of results would look like under these conditions if the cue were peripheral? Explain why.

Question 4. In our experiment you did not have to remember any items in memory while performing the task (i.e., there was no memory load). Suppose that, instead, we ran the same experiment, but this time asked you to remember 6 different digits during each trial. What do you think the pattern of results would look like under these conditions if the cue were central? What do you think the pattern of results would look like under these conditions if the cue were peripheral? Explain why.