By Kevin Chan

In a scene in the ever famous Spider-man movie, Mary Jane is being mugged by four men. Spiderman thro

ws two of the men into two different windows behind Mary Jane. The camera then focuses on Spiderman beating up two other muggers . When the camera turns back to Mary Jan, the two previously broken windows are seen intact again.

Bizarre? Not quite, a similar glass recuperating incident occurred in Terminator 2: Judgement Day. In this scene, the T-1000 robot punches his body through the window of a helicopter in order to enter the helicopter. Later, when the camera zooms out of the shot, the window has no damage what-so-ever. Unfortunately, these aren't findings of glass magically repairing itself, rather these are simply errors in movie production called continuity errors. There are so many movies that have glitches of small details of just about anything. Even the biggest

budget movies like Harry Potter, The Matrix, Star Wars and previously mentioned Spiderman have such errors.

It is amazing that we do not notice these errors. (Or do you actually notice these small glitches because I for one DO NOT). The big question is, why? why do we not actually notice such things? When we watch a movie we usually give our 100% focused attention to both the audio visual aspect of the film. USUALLY, unless of course the movie is insanely a bore. Why then, do we not usually notice these things.

Similar to the study, which started with mentioning change blindness, I will use change blindness as an introduction to the core concept being studied, change blindness. In particular, the

researchers studied change blindness in eyewitness testimonies.

The methodology was simple, participants were to watch a video depicting an opportunity theft from a student house. The actor who played the burglar would change into another actor half way throughout the video. It is important to note that their differences were very much evident (such as in height, built and details of their clothing.)

Participants were then randomly sorted into either a intentional condition wherein they were told "you are about to watch a short video. Pay careful attention to the content, as there will be a memory test later" or a incidental condition "this short video illustrates the ease and frequency of burglaries of student accommodation and the importance of keeping houses secure". Hence, in the second condition, they were not induced to really focus on details of the video. Then a questionnaire was given to them to see if they noticed anything different.

Results show that 65% of participants in the intentional condition were able to notice a change while only 12.5% of the participants in the incidental condition was able to notice this. Also, they were able to conclude that females were more sensitive to changes but only in the intentional condition.

They explain that people who exhibit change blindness may lack a detailed representation of the initial actor and rely on a gist memory that gives a gross discrepancy in appearance of the second actor.

Their study stated that the authors were able to conclude that the poor performance (of those who did not notice the change) to a simple lack of representing the original target. It requires the observer to form a visual representation of the original stimulus that can be tracked over time to form a basis for later recognition. Hence, the secret to change blindness is actually explicit rather than implicit processing.

This posses the question, how reliable then are witness to actual crimes. Since witnesses usually do not have any idea that they are about to witness a crime, it can be said that they are under the incidental condition. That is, they are not told you concentrate on the things they see and to memorize their environment. Wouldn't that make their claim very much fallible? Especially if they are under trauma or shock during the actually crime scene.

I just found it a good point to dwell on especially in the court room. How valid is a claim by a witness? If only 12.5% of the participants in the incidental condition were able to remember the face of the burglar, is that synonymous to saying only 12.5% of these people have a clear visual representation of the perpetrator? Since their literature suggests that they need visual representation of the original stimulus, this means that they were not able to create visual representation of the stimulus. Hence, they were not able to create into their working memory an image of the burglar.

Getting back to continuity errors, that is probably why we are not able to see glitches in movies. When we go to a movie although it seems that our 100% attention is focused on the movie, we are relaxed. If before watching a movie we are told that a memory test would be shown after the movie, we might be able to spot some continuity errors. In fact, we are want to look for continuity errors we can probably do so. But this will entail probably forgoing the story line, jokes, conversation and simply relaxing.

Davies, G. & Hine, S. (2007). Change Blindness and Eyewitness Testimony. The Journal of Psychology: 141 (4): 423-434.