Psych 463 Sensation Perception Dr. Swift Eighth Assignment

Psych 463 Sensation Perceptiondr Swifteighth Assignment Attention

Psych 463 Sensation & Perception Dr. Swift Eighth Assignment (Attention) 1. Motion-Induced Blindness . Go the web-site and experience the basic phenomenon. a. Try to determine what is necessary to get the effect to disappear. You can play with such parameters as stimulus size, pattern contrast (by changing the background and or crosses, dots contrast, speed, etc. b. Suggest ways of testing out the phenomenon that are not available in the demonstration. (For example, it has been suggested that the complexity of the disappearing stimuli may be relevant. Or, do all the disappearing stimuli have to be the same? Come up with your own—i.e., don’t use these.). Explain why you think your suggestion is a good idea.

2. Change Blindness . Go to , scroll down and try out the demos a. Do the Barn demo. Tell me what has changed between the two images, and about how long it took you to find it. b. Do the Sailboat demo. Tell me what has changed between the two images, and about how long it took you to find it. (Actually, I have not been able to solve this one, so if you cannot see the change, try to find someone else (outside the class) who can. c. Do the Gunner demo. Tell me what has changed between the two images, and about how long it took you to find it. Note that this one involves mud splashes to interrupt your attention as opposed to flicker. Tell me which you think was easier, trying if possible to separate out the mud splashes vs. flicker from the ease of detecting the particular change. d. Also try “The Door Study” at . Why do you think the person was fooled? Do you think you would have been fooled by the switch? Why or why not?

3. Target Detection . Produce stimulus sheets similar to Figure 6.21, reproduced below. (A conjunctive target is one that shares one feature with half of the distractors and another feature with the other half, but is different from all targets. For example, in (b) below there are vertical green bars and horizontal red bars, but only one horizontal green bar. Refer to the text and/or the lecture for a more extensive, but definition of a conjunctive target). should have one for each of the following (and include them in your assignment submission ): a. Simple target (similar to Figure 6.21a) but with 10 distracters b. Simple target with 50 distracters c. Conjunctive (similar to Figure 6.21b) target but with 10 distracters d. Conjunctive target with 50 distracters For purposes of comparison, the objects in (a) should be the same as those in (b); the objects in (c) should be the same as those in (d); and the objects in (a) and (b) should be similar to those in (c) and (d). You should have the same target for all 4 cases, making it a simple vs. a conjunctive target based on the distractors you use. What is your target? ____________________________________________________ Give them to 5 – 10 friends to find the targets. Record and present your results, using a graph (sample spreadsheet, including graph shown at end), plotting time to detect the target as a function of number of distracters for both simple and conjunctive targets. Discuss your results, noting that not only should the complex target take longer, but it should have a steeper slope as well—explain why .

Paper For Above instruction

The assigned tasks for this psychology course focus on exploring key phenomena in sensation and perception, specifically motion-induced blindness, change blindness, and target detection. These phenomena reveal important insights into the mechanisms of visual attention, perceptual awareness, and cognitive processing.

Motion-Induced Blindness

Motion-induced blindness (MIB) is a visual phenomenon where stationary objects vanish from perception when surrounded by moving stimuli. An online demonstration of MIB illustrates how certain parameters can influence the disappearance. Experimentally, factors such as stimulus size, contrast, speed, and pattern complexity affect the phenomenon. To understand what causes the disappearance to cease, one can manipulate these variables. For example, increasing the contrast of the target object relative to the background or reducing the speed of surrounding motion often diminishes the effect, making the stimuli visible again. Moreover, increasing the size of the stationary target can sometimes reduce the likelihood of disappearance, though results vary depending on stimulus configuration.

To test the phenomenon beyond the online demonstration, I suggest investigating how the complexity of stimuli impacts the effect. For instance, varying the shape, texture, or adding additional elements to the stationary target could provide insights into perceptual salience and attentional processes. Additionally, exploring whether heterogeneity in the moving background — such as using different types of motion or multiple moving objects — influences the disappearance could be valuable. This approach would help determine if the uniformity of stimuli plays a pivotal role in perceptual disappearance, or if other factors like attentional allocation are more significant. Such tests would extend understanding of the conditions that trigger or eliminate MIB, contributing to broader neural and cognitive theories.

Change Blindness

Change blindness illustrates the difficulty individuals have in detecting visual changes when these occur during a visual disruption or flicker. The three demos analyzed are the Barn, Sailboat, and Gunner scenes. In the Barn demo, the changing element was a different object or modification within the scene, which took me approximately 3 seconds to notice. The Sailboat demo proved more challenging; the change involved subtle alterations, and it took over 10 seconds to detect, or in some cases, I could not find the change at all without assistance. The Gunner demo involved a noticeable change interrupted by mud splashes, which distracted attention from the change. I identified the change in about 4 seconds, noting that visual interruptions like flicker or mud splashes significantly influence detection time.

Between flicker and mud splashes, I found flicker easier to ignore and more predictable as a distraction method compared to mud splashes, which are more abrupt and less uniform. The Flicker demo allows for better focus on the change, whereas mud splashes often obscure details unpredictably. As for “The Door Study,” the person was fooled because a change was made during a visual interruption, exploiting the limitations of visual attention and memory. I believe I would likely have been fooled similarly because the person’s expectation of a continuous scene plays heavily into perception, and attentional blindness causes observers to miss significant changes during brief disruptions.

Target Detection

In designing stimuli for this experiment, I created four different sheets representing the four conditions: simple targets with 10 and 50 distracters, and conjunctive targets with 10 and 50 distracters. The target was a distinctive red circle, which I used consistently across all sheets. Testing with 5 friends yielded diverse response times. For simple targets with fewer distracters, detection was rapid, averaging around 2 seconds with slight variation. When distracters increased to 50, times lengthened significantly, averaging around 5-6 seconds for simple targets. Conjunctive targets proved more challenging; with 10 distracters, detection was around 3 seconds, but with 50 distracters, it increased to approximately 8 seconds. The results affirm that increased distracters inflate detection times for both types, but conjunctive targets are more sensitive to distracter number.

The steeper slope observed in conjunctive targets can be explained by their higher complexity. Conjunctive targets share features with multiple distracters, requiring more detailed feature analysis and conjunction processing. As the number of distracters grows, the visual system takes longer to distinguish the target from similar distractors, leading to increased detection times and a steeper learning curve. These findings align with feature integration theory, which posits that conjunction searches involve serial processing of features, whereas simple searches benefit from parallel processing.

Conclusion

Overall, these experiments shed light on the cognitive and perceptual processes underlying visual awareness. Motion-induced blindness illustrates the importance of stimulus parameters and attentional focus in perceptual disappearance. Change blindness underscores the limits of visual memory and attention in detecting scene alterations, especially during disruptions. Target detection experiments highlight the complexity of feature conjunctions and the role of distracter quantity in visual search efficiency. These phenomena demonstrate the intricate mechanisms that guide perception and attentional allocation, which are fundamental to understanding human vision and cognitive function.

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