Talk:Phi phenomenon

message: Isn't this the basis of tv? a bunch of images being flashed on screen, each one slightly different then the last? there is no real motion non tv either, just us perceiving motion from rapid succession of still shots.
:You're talking about the gif, I take it...Yeah, it is, as far as I can see. This is beta!
:It's not exactly my area of specialization, but it seems pretty damn clear to me that it's not phi. The only "motion" I see is the brightened yellow disk moving around all over the place, so if this is a phi gif I need to contact my shrink and tell her I'm the only human being ever to see shapes in my phi. Really now...in an article whose gist, and rightly so, is how easily phi is confused with beta, wikipedia's illustration of what phi really is, is in fact a perfect illustration of beta? I'm deleting this B.S. before any more of America's famously vision-theory-obsessed teenagers get led astray by it, and we start losing out to the Communist kids who are getting their phi information from people who know what they're talking about.205.212.73.217 09:27, 31 May 2007 (UTC)
replies: text: Oh! I had to read this discussion before I understood, so I think the gif for phi movement should be sped up.   — Preceding unsigned comment added by 81.174.157.213 (talk) 10:38, 19 August 2011 (UTC)
thread_title: Untitled

message: The article currently states: "The phi phenomenon is similar to beta movement in that both cause sensation of movement; however, the phi phenomenon is an apparent movement caused by luminous impulses in sequence, whereas beta movement is an apparent movement caused by luminous stationary impulses"
This doesn't explain the difference AT ALL. To me, both sentences seem to be saying the same with slightly different words. What's the difference between "luminous impulses in sequence" and "luminous stationary impulses"? It doesn't help that in both cases the impulses are "stationary"; there is no actual movement.
Please, can someone who understands this explain the difference in clear terms? 200.0.230.234 (talk) 12:01, 2 October 2013 (UTC)
replies: text: This article is indeed a bit unclear and the illustrations are accurate but they don't make the best distinction between the phenomena. Here is the important difference: notice that in the phi phenomenon, all of the points of movement are present, and one is getting "covered up" in each new frame. That creates the sequence. In beta movement, a single new dot is present each position, and it is the continual refreshing of the dot that creates the illusion of sequence. I think that's the main distinction between the two, though I could be off. Here is a different sample of beta movement. The difference is a little hard to verbalize, but I hope this helps a little. The page is definitely far too ambiguous. ~ Boomur [☎] 22:07, 3 October 2013 (UTC)
replies: text:  I think the two related articles here are seriously confusing. Based on the "Experimental demonstration" section, , , and the Motion perception article section on first-order perception, maybe a clearer explanation is possible. From the article: "The classic phi phenomenon experiment involves a viewer or audience watching a screen, upon which the experimenter projects two images in succession. The first image depicts a line on the left side of the frame. The second image depicts a line on the right side of the frame. The time/lag (the inter-stimulus interval, ISI) between offset of the first and onset of the second line is varied." With a very low lag between the image flashes, you get the phi phenomenon where there's apparent motion of an occluding "object" (the same color as the background) passing over the lines. With more lag between the flashes, you get beta movement where the object itself appears to move. In beta movement, the object shown in each frame appears to move, whereas in the phi phenomenon there are two objects and something appears to be moving between and over them. 2601:196:4700:30AF:1909:F3FE:2E74:E777 (talk) 01:27, 23 January 2017 (UTC)
thread_title:  Unclear difference between Phi phenomenon and Beta movement 

message: I think this article would benefit from injecting some references from the literature, which contradict much of the information on this page. In this article from Vision Science, published in 2000, Robert Steinman, Zyg Pizlo, and Filip Pizlo review Wertheimer's original article, plus some early follow-ups, and carry out controlled replications of the phenomenon in an attempt to set the record straight on the difference between phi and beta. 
For one, Wertheimer produced both phi and beta movement with the same pair of slits, contradicting the assertion that 'beta movement is between different points in space, whereas phi is between different images at the same point.' In fact, beta motion (also known as "optimal motion") occurs when the lights are switching about every 60ms. Beta is the phenomenon where it looks like the light is moving continuously from one to another (the kind found in cinema). 
If you make it slightly faster, somewhere in the region between beta motion and simultaneity, people see an ambiguously shaped dark region flickering or shifting in the middle of the two different points. 'Disembodied movement.' This is phi. It's significant because your visual system is actually forming a qualitatively new, primitive object from the sources, not just smooth continuous movement of existing sources. There's a visual demonstration by the authors here.
This account is backed up independently by Stephen Palmer's excellent textbook Vision Science (see p. 472 and Fig. 10.1.6) and, of course, Wertheimer's original 1912 paper, available since 2012 in English translation through MIT Press. I'm new to editing articles, but if everyone can agree on these sources, I'd be happy to make the changes to the page. 99.108.224.87 (talk) 06:04, 4 April 2014 (UTC)
thread_title:  Introducing some new references 

message: Why is it called φ? Ventifax (talk) 06:57, 12 July 2020 (UTC)
thread_title:  Explain the name 

message: What is the 'apparent movement' that is supposed to be seen in the image?  The introduction is to vague to know what is being talked about?  Is the blinking the movement?  It seems unlikely from the text.  But I don't see any other movement. Kdammers (talk) 06:59, 17 September 2020 (UTC)
replies: text: I suppose you're talking about the GIF at the top, which indeed may just seem to be two blinking bars. If you look at the blue dots in the "magni-phi" GIF a bit lower in the article, the effect is much clearer: there seems to be some vague white shape running around the circle. Something similar can be seen happening between the bars in the top GIF, something like a brighter phantom version taking the place of each bar in turn. It would probably be much clearer when projected on a large screen with less distraction in the surroundings, but it's possible to focus your mind on seeing a grey shape jumping back and forth instead of focusing on the dark bars. Of course the vague shape is just what we perceive to be the parts of the background that would be hiding behind the dots or bars and seem to be revealed during the moment that a dot or bar is no longer seen. Our mind just tries to make sense of these abstract shapes and colours in ways that it has been conditioned by looking at real moving objects all our life. This "Phi phenomenon" seems to be on the brink where the interpretation of two blinking objects starts to give way to the interpretation that the "background" is actually a moving object, because it starts to follow the pattern of how we usually see a moving object.Joortje1 (talk) 12:00, 13 February 2021 (UTC)
thread_title:  Movement 

message: The flashing images in the article could potentially trigger epileptic seizures. Bigbergice (talk) 11:41, 2 February 2023 (UTC)
thread_title:  Potentially problematic image