Hartej Gill Professor RehderMay 4, 2017TA: EstiObject appearance, disappearance, and attention prioritization in Real-World ScenesThe primary field of study for this article is the goal directed orientation of attention. What the experimenters are curious about is the phenomenon that follows when distinctive features, "objects that attract attention" (1061), distract someone from other stimuli, despite that distractor being irrelevant to whatever goal is trying to be accomplished. These distracting stimuli can manifest themselves in several ways; like "abrupt appearance of a new object" (1061), sudden disappearance of an already existing object or even objects simply of unique color, shape and movement. This idea is of being distracted by a stimulus within a field of vision that isn't related to the initial goal is called attention capture. To study attention effectively, it is essential to establish what kind of scene the subject is viewing before distracting stimuli can be introduced, and their reaction assessed. A scene from the world would present way too many unique stimuli that would all distract a subject's attention,not allowing for any significant theory to be drawn. Past study has then shown that capture effects may only be present in a tightly monitored, laboratory setting and not be applicable to the real world. Brockmole and Henderson seek to reevaluate whether attention capture effects are applicable to the real worlds as they are in laboratory settings. We already have established, via experiments by various researchers in the past, that attention capture is possible by irrelevant stimuli. The complexity of real world scenes makes it difficult to apply this theory to everyday attention. A previous study on the same subject matter by Brockmole and Henderson had measured subjects' eyes ability to move on to a new, abruptly shown object within a real world scene. The results showed that human eyes, whether moving quickly or still, are directed to foreign objects faster than could be due to chance. Furthermore, this experiment established that attention could be shifted by distractors in real world scenes. Theprocess by which it occurred involved two different mechanisms; either immediate detection while the eye was moving rapidly, with the presence of a transient signal, or delayed detection over several "saccades" without a transient signal. The current study addressed by the article continued along these lines, furthering the understanding of attention in real world scenes. After conducting their first real world scene experiment, Brockmole and Henderson set out to quantify the degree to which capture may occur, either by presenting a distracting object within the scene, or removing an already present object from the scene. Previous study into this arena has shown that transient onsets allow for faster attention capture than transient offsets, despite the widely held belief that they are equivalent in their ability to attract attention. This experiment sought to expand on the difference in "prioritization" between onset and offset transient signals juxtaposed with the appearance and disappearance of distracting objects. The means by which the experimenters were going to find data to support this hypothesis was by having subjects view photos of real world scenes while their eye movement was examined in real time. Eye movement was the primary indicator of attention capture within the scene. During each trial, a distracting object was either removed or added to the scene. The region wherever the objected was added/removed was defined as the "most salient region." To operationalize the speed of prioritization for further experimentation, the researchers counted the number of saccades between an objects appearance or disappearance, depending on the trial at hand. The frequency of detection was operationalized by using the probability of fixation on to the changing region after the disappearance/appearance occurred. A second leg of the experiment similarly measured stimuli's ability to capture subjects' attention with disappearing and appearing objects within a scene, during both a saccade and fixation. The fixation condition of this second tier allowed for a contrasting analysis of the difference between salience for disappearance and appearance of objects. The saccade condition allowed the researchers to see whether memory played a role in the prioritization of objectdeletion within a real world scene. This introduction of memory's involvement is justified by previous tests where it was found that added elements to a visual scene were detected better than were deleted elements from the same scene, in general. The primary hypothesis of the experiment as a whole is that "prioritization of new and deleted objects, in the saccade condition,could allow determination for how memory of a scene can be used to locate different types of scene changes."The subjects of this experiment were sixteen Michigan State University undergraduate students. They were shown 30 full color photographs each that depicted real world scenes. There were two photographs in addition to each original photograph, one where a certain element was eliminated, and one where that same element was added when it was not present initially. There was also a condition where subjects were to either fixate on the center on the scene and then shiftto the area of importance or have their eyes moving, then shift to the area of importance. Subjects were randomly assigned to either the added element condition or the eliminated elementcondition. They were to memorize the scene, then be presented with the scene again with a singledetail missing. Then, subjects were to view the new image that appeared instantaneously after thefirst, then depending on when their eyes crossed the midline of the display. The time it took for their eyes to view the change and the frequency with which the critical region was fixated upon, is what was measured. There was a specific region which contained the added/deleted object, that once the eyes tracked within it, the clock was stopped. The protocol was that the first four fixations that occurred after The means by which the researchers monitored eye movement was by calibrating a ISCAN ETL machine, with a chin and forehead rest for stability, constantly throughout the experiment. The independent variable of the study is the nature of the object change; with sub-categories of object addition