Change Blindness with   1Running head: CHANGE BLINDNESS WITH THEME AND OBJECT CHANGE        Change Blindness with Scene Th...
Change Blindness with     2                                             AbstractPeople often times fail to detect changes ...
Change Blindness with        3            Change Blindness with Scene Themes and Adding and Deleting Objects       All thr...
Change Blindness with       4woman with the umbrella was noticed more often, suggesting that something that belongs less i...
Change Blindness with         5the beginning they would need to later identify a possible change, deletions were recognize...
Change Blindness with        6Procedure       Participants were greeted as they arrived and asked to sit in one of eight r...
Change Blindness with         7addition or deletion. A two-factor ANOVA was conducted based on reaction time for the twoin...
Change Blindness with        8identify whether a participant noticed a change or not. The letters K and D were ambiguous a...
Change Blindness with   9                                           ReferencesAgostinelli, G., Sherman, S. J., Fazio, R. H...
Change Blindness with   10Table 1Time Taken to Identify Change in Theme Condition_________________________________________...
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Change Blindness With Scene Themes And Adding And Deleting Objects

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People often times fail to detect changes in scenes they observe. We examined theme, whether an object was related to a scene or not, as well as object change, whether the object was added or deleted to the previous scene, would effect the reaction time in identifying a change. Participants were randomly assigned to one of two object change conditions (add or delete) and then were asked to judge whether or not there was a change involving scenes with related objects changing, as well as scenes with unrelated objects changing. The results showed a main effect of theme but no main effect of object change as well as no interaction between the two independent variables.

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Transcript of "Change Blindness With Scene Themes And Adding And Deleting Objects"

  1. 1. Change Blindness with 1Running head: CHANGE BLINDNESS WITH THEME AND OBJECT CHANGE Change Blindness with Scene Themes and Adding and Deleting Objects Gina M. Martino Northern Illinois University
  2. 2. Change Blindness with 2 AbstractPeople often times fail to detect changes in scenes they observe. We examined theme, whetheran object was related to a scene or not, as well as object change, whether the object was added ordeleted to the previous scene, would effect the reaction time in identifying a change. Participantswere randomly assigned to one of two object change conditions (add or delete) and then wereasked to judge whether or not there was a change involving scenes with related objects changing,as well as scenes with unrelated objects changing. The results showed a main effect of theme butno main effect of object change as well as no interaction between the two independent variables.
  3. 3. Change Blindness with 3 Change Blindness with Scene Themes and Adding and Deleting Objects All throughout history, humans have placed a lot of faith in the accuracy ofunderstanding and remembering the scenes, events, and people they see. A perfect example ofthis is eyewitness testimonies in crime investigations. These rely on individuals to recallsomething they saw over an extended time period. However, there is some evidence to suggestthat people cannot even accurately identify something that has just happened, or is happeningright before them. Everyday people are exposed to a myriad of visual information, so it onlymakes sense that there would be some discrepancy in a person’s recollection of events. Certain studies have examined the meaningfulness of an object determining how easilydetectable a change in it would be. In one experiment, the ease in detecting change in faces wascompared with the ease in detecting change in other common objects. Although participantsreported detecting change in faces to be one of the more difficult tasks, there was a good deallower percentage of error in detecting change in faces than all the other objects used, suggestingthat a person may perceive a task as more difficult than it is (Ro, Russell, & Lavie, 2001). Other studies suggest that if a person’s attention is focused on something, they will notnotice an unexpected object or occurrence. Simons and Chabris (1999) explored this theory in anexperiment in which participants were asked to count how many times a basketball passedbetween members of a team. While the participants’ attention was focused on this activity, aperson in a gorilla suit or a woman with an umbrella would walk through the middle of thescene. The gorilla or the woman with the umbrella was used as a way to test whether an objectmore or less related to the scene would be more noticeable. Whether or not the person noticedthis out of place individual passing through was then questioned. It was found that the
  4. 4. Change Blindness with 4woman with the umbrella was noticed more often, suggesting that something that belongs less inthe scene was least likely to be noticed. Hollingworth, Williams, and Henderson (2001) also explored whether an object fits withthe scene or not determines how noticeable it is, however they went further with this to explorewhether the details of the scene decay immediately or if they are stored in the brain for lateraccess. Their results showed evidence that details are indeed stored for longer periods of time,and more so when the object does not fit with the scene. Most previous experimentation on change blindness was done using images or videos ona computer or projected by some other device. Simons and Levin (1998) saw this as a possibleinfluence on the ability of people to detect change and decided to create an experiment using reallife observations of participants. In this experiment, the change would happen right in front ofunknowing participants eyes as a door passed between the participant and the experimenter whilethe experimenter changed places with one of the men carrying the door. Overall, there are two ways in which a person can recognize change: detection andidentification. Often times, a person is able to detect that a change has occurred, and they mayeven be able to identify the general area in which it occurred, however they cannot always tellwhat specifically changed (Rensink, 2002; Agostinelli, Sherman, Fazio, & Hearst, 1986). Utilizing changes within ambiguous and meaningful images, Agostinelli et al (1986) setout to support the hypothesis that when an object was added to a previous scene, it would beeasier for participants to identify the object than if the object were deleted from the scene. Intheir first experiment where participants were unaware that they would have to identify a change,this hypothesis was supported. However, during the second experiment, participants were told at
  5. 5. Change Blindness with 5the beginning they would need to later identify a possible change, deletions were recognizedwith more accuracy therefore not supporting the hypothesis. The present study believes in two hypotheses. First based on Hollingworth, that objectsthat are unrelated to the scene they are in are more likely to be noticed than objects that belong.For instance, an office chair outside will be more noticeable than whether or not someone iswearing shoes indoors. The second hypothesis based on Agostinelli, is that the deletion of anobject from a scene will be more easily noticed than the addition of the same object to the samescene. MethodsParticipants Thirty-six introductory psychology students from a Midwestern University participated inthe experiment for class credit. Participants were randomly assigned to one of two object changeconditions, 16 to the add condition and 20 to the delete condition.Materials The experiment will be conducted using ePrime stimulus presentation on computers inindividual rooms. Pairs of pictures were constructed to be shown in varying order. Each paircontained on change which was either related or unrelated. For example, one scene was of asnowboarder outside and the object that was changed was a shadow in the background, this itemfit naturally into the scene. Another scene was of two people talking outside and the object thatchanged was a bright green indoor chair. In one condition, participants saw the change as anaddition to the previous image , in the other condition they saw the change as a deletion from theprevious image.
  6. 6. Change Blindness with 6Procedure Participants were greeted as they arrived and asked to sit in one of eight rooms. Theywere asked by an experimenter to read and sign an informed consent form before continuingwith the experiment. This experiment was a 2x2 design. Participants were randomly assigned asthey arrived to one of two between subject object change conditions, add or delete, which servedas the first independent variable. For example, in the add condition, a scene was shown of a hotelroom with a blank wall, and in the second scene the wall would have a picture on it. The secondindependent variable, theme, occurred within subjects. The two levels were related andunrelated, and were based on whether the change involved something that would naturally occurin the scene or not. The experimenter read the instructions to the participant that was displayedon the computer screen. Participants were then presented with one scene until they pressed a keyto continue. After pressing the key, there was a 2000ms blank screen and then the same sceneagain only with some alteration. The difference between the two conditions was that the secondscene either had something added to it, or subtracted from it. Participants then had to decide ifsomething in the second scene changed or not by pressing the “d” key if they saw no change, orthe “k” key if they saw a change. If they decided that it has changed, they were asked to typewhat it was that changed in the following screen. All scenes contained a change. When finishedwith all the scenes, the participants were told to notify the experimenter that they were finishedand were then given a debriefing form explaining the purpose of the experiment. Results This experiment set out to find whether there is an effect on change blindness based onwhether an object is related or unrelated, as well as whether or not an object is presented as an
  7. 7. Change Blindness with 7addition or deletion. A two-factor ANOVA was conducted based on reaction time for the twoindependent variables (theme and object change). The first hypotheses regarding the effect oftheme (related vs. unrelated) was supported as the data showed a main effect for theme, F(1, 34)= 12.30, MSE = 852345.719, p < .01. See Table 1 for means and standard deviation. This effectsupports the prediction that individuals are quicker to respond to unrelated objects(M=3665.7500, SD=1752.92145) than to related objects (M=4406.0278, SD=1824.67554).However, the second hypotheses regarding the effect of object change (add vs. delete) was notsupported. The data showed no main effect for object change, F(1, 34) = 1.23, MSE =5505618.859, p >.05. This suggests that individuals are no quicker to notice a change whether itis added to the scene or deleted from the scene. The data also showed no significant interactionbetween theme and condition, F(1, 34) = 1.299, MSE = 852345.719, p > .05. This serves tosuggest further, that whether an object is added or deleted does not effect a person’s reactiontime, regardless of whether the object involved was related or unrelated. Discussion The goal of this study was to examine change blindness and the effects of certain visualvariables on an individual’s reaction time. The results showed that while whether an object wasrelated to a scene or not did have an effect on reaction time, whether that object was added to ordeleted from the previous seen had no apparent effect. This supports the first hypotheses, but notthe second. Also, when examining the relationship to previous studies on change blindness, wesee that the data supports the conclusion of Hollingworth et al. (2001), while challenging that ofAgostenelli et al. (1986). One particular problem I saw with the procedure of the experiment, was the keys used to
  8. 8. Change Blindness with 8identify whether a participant noticed a change or not. The letters K and D were ambiguous andcould have caused a greater delay in reaction time than if more related letters were used. Evenmore detrimental, the delay may have been greater for the first few slides, but the participantsmay have sped up as they went along. To control for this difficulty, several things could be donein the future. First, the letters chosen could be more related, such as Y an N (for yes there is achange and no there is no change) or C and N (change and no change). Finally, a key statingwhich key to press could be added to the images or placed on the computer monitor, althoughthis again could cause a difference in speed over the course of the experiment.
  9. 9. Change Blindness with 9 ReferencesAgostinelli, G., Sherman, S. J., Fazio, R. H., & Hearst, E. S. (1986). Detecting and identifying change: Additions versus deletions. Journal of Experimental Psychology, 12(4), 445-454.Hollingworth, A., Williams, C. C., & Henderson, J. M. (2001). To see and remember: Visually specific information is retained in memory from previously attended objects in natural scenes. Psychonomic Bulletin & Review, 8(4), 761-768.Rensink, R. A. (2002). Change detection. Annual Review of Psychology., 53, 245-277.Ro, T., Russell, C., & Lavie, N. (2001). Changing faces: A detection advantage in the flicker paradigm. American Psychological Science, 12(1), 94-99.Simons, D. J., & Chabris, C. F. (1999). Gorillas in our midst: Sustained inattentional blindness for dynamic events. Perception, 28, 1059-1074.Simons, D. J., & Levin, D. T. (1998). Failure to detect changes to people during a real- world interaction. Psychonomic Bulletin & Review, 5(4), 644-649.
  10. 10. Change Blindness with 10Table 1Time Taken to Identify Change in Theme Condition______________________________________________________________________________ Mean Standard deviation______________________________________________________________________________Unrelated reaction time (ms) 3665.7500 1752.92145Related reaction time (ms) 4406.0278 1824.67554______________________________________________________________________________

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