You Thought You’ve Seen it All...

Prior to learning the topics in Perception, we, people think that we see objective reality through our eyes. Yet we’ve learned that change blindness occurs and this is when we fail to notice or detect changes in the scenes where we’ve set our eyes upon for a brief period of time. It would seem logical to think that small modifications or tiny changes would be difficult to detect while larger ones would be more noticeable and may not even be subjected to the phenomenon of change blindness. However, the latter assumption was contradicted by Rosielle and Scaggs’ research findings (2007).

In the pursuit to investigate the ability of people to detect large changes in the scenes and at the same time to measure change-blindness blindness, the study involved a sum of 144 students; 48 participants randomly assigned to each of the three conditions and who reported to have normal or corrected-to-normal vision and to have attended the university for at least 2 years. The three conditions are: 1.) Change-Detection group wherein the task of the participants were to study each of the 12 images of their own campuses presented one at a time, each for 20 seconds, and to determine if something is missing, and in case there are any, what were they; also, they were asked to rate their familiarity with the scene and to estimate the number of times per week that they personally viewed the scene in the past academic year; 2.) Familiar-prediction and 3.) Unfamiliar-prediction groups are the other tow conditions. In these conditions, the same task of estimating the percentage of undergraduate students who would notice the changes (the same set of stimuli were used for all the conditions including the first one); the only difference in these two prediction groups is their familiarity to the scenes. Only those who did not attend the universities featured in the stimuli were included in the unfamiliar-prediction group, unless otherwise. In my opinion, the researchers were able to conduct the study very well through these methods and strategies that they had employed. In addition, it was a good idea to analyze how familiarity would affect change-blindness blindness.

To continue,the stimuli used in the study were 24 color images of specific locations from two college campuses. These stimuli were presented in color on a 17-inch color monitor with a resolution of 800x600. An altered version of each scene was edited to digitally remove prominent objects/features in the scene (i.e. buildings, landscapes).


As mentioned, the stimuli did not only include large changes, but they were also scenes from familiar environment of the participants. Yes, that’s right! The scenes were even familiar to the subjects thus it could be assumed that the changes would be obvious enough to increase the change-detection probability. Some literature suggests that processing a familiar environment would involve long-term memory. So what if it involves long-term memory? Well, it is actually assumed that long-term memory contains detailed information about objects seen in the past (Henderson & Hollingworth, 2003; Hollingworth, 2004; cited in Rosielle & Scagss, 2007). Melcher’s study (2006) also suggests that the amount of information about a scene stored in the long-term memory accumulates over time— that is increased familiarity— which is probably why the participants in Change-detection and Familiar-prediction conditions of Rosielle and Scaggs’ study were limited to those who had attended the university for at least two years. In addition to this, Atkinson and Shiffrin (1968) also found that increasing the number of exposure improves memory for scenes; thus multiple exposures to the environment, like going to a university campus on a regular basis, would seem to lead to a robust and also a detailed memory representation of that environment. Why do we say that familiar environment and scenes are stored in the long-term memory? That is because the features of such environment are said to also have practical uses beyond our recognition, such as being landmarks, that gives it a good reason for us to unconsciously encode it in our long-term memory and in turn be a “good candidate for immunity to change blindness” (Rosielle & Scaggs, 2007).


But is this really the case? As mentioned above, we would suppose so.

In fact, in the prediction of the study which measures change-blindness blindness— that is in short explanation, the overestimation of the ability to detect changes in scenes when in fact change blindness does actually occur— it has been found that both the familiar and unfamiliar group of participants overestimated the easiness of change-detection in stimuli that were also presented in the change-identification condition. Both of the groups predicted better performance compare to the actual result of the change-detection group’s performance. However, the familiar-prediction group’s estimate was relatively more accurate. Interestingly, the unfamiliar group’s prediction was correlated to the area of change (r= -.811, p<.01), meaning this groups’ prediction of difficulty is based on the size of the object that was changed or removed (Rosielle & Scaggs, 2007).

But then again, is this really the case? The answer…? A big NO!

As implied in the previous paragraph, participants in the change-detection condition had actually failed to detect 81% of these “big changes” despite reports of high familiarity and recognition of these familiar locations 97% of the time.

A plausible explanation why people are unable to see changes, even such larger ones discussed in the literature, is that people are not confronted to such changes in real life (Rosielle & Scaggs, 2007). Buildings and landscapes such as fountains don’t disappear or appear in just a blink of an eye; and so it might be the case that our visual system did not just evolved in such way which gives us difficulty to perform detection of the similar changes. Without movement or motion, our visual system cannot perceive changes in the stimulus or in the environment (Goldstein, 2010).

Overall, the study was remarkable as it was able to examine not only the change blindness of people, specifically to big changes, but also how we could be blinded by our believes and senses. Reading this study had also made me think if change blindness could be associated to the notion that people are resistant to change in a social level. Could there somehow be a link between these?

Finally, as this study simply suggests that people are not that aware of his and her environment though they may subjectively think they are, it makes us-- or at least me-- wonder more about our "real world" and if there really is an objective reality. Is there really an objective reality? Who knows (when the study had just shown how vulnerable we are to "trickery"!)???

...So if you thought you’ve seen it all, you better think and look again!


References:
Goldstein, E. B. (2010). Sensation and perception (8th ed.). California, USA: Wadsworth.

Rosielle, L. & Scaggs, W. J. (2007). What if they knocked down the library and nobody noticed? The failure to detect large changes to familiar scenes. Memory. 16 (2). 115-124. Retrieved from EBSCOhost.