I have just seen the entire page 1 results change in one go?

Selected answers from the Dumb SEO Questions Facebook & G+ community.

• 
  Lewis Barrs: Hi,
  
  I have just seen the entire page 1 results change in one go??
  The 10 sites ranking on page 1 have completely changed to 10 new sites regarding SEO related words, i.e SEO services, SEO company etc.
  
  There is no way whatsoever that all 10 have been slapped at the same time so Google have picked up all 10 and give 10 new sites a shot on page 1 regardless of power.
  
  JOKE
• 
  Andy Wigglesworth: +Lewis Barrs ;sorry to ask, are you searching while logged in? ie, SPYW? - have you done the same test incognito in chrome?
• 
  Lewis Barrs: Yes all of the above a complete switch, the ip location from where you are searching is a factor also but this is 100% the case as the results are based from the same location with regards to generic phrases, i.e seo company.
• 
  Paul Lovell: +Lewis Barrs matt cutts did say the other day that the serp will be changing twice a day on avg.as google are updating the algo on avg.
• 
  Lewis Barrs: +Paul Lovell ; apparently so but this is a different scenario I believe.  ;Are we saying that the top 10 results just so happen to drop dramatically with a standard algo update? Also this has been happening within the places results, top 10 place listings suddenly change to another 10 then back again a few weeks later.  ;
• 
  Paul Lovell: Was you logged into Google then logged out? This may be another explanation
• 
  Lewis Barrs: Not that, this did actually happen without a doubt
• 
  Daniel Sanchez: +Lewis Barrs, Not saying it didn't really change but maybe you should also check this out
  
  While logged out make sure you disable personalized search ( Google still personalizes logged out search )
  
  http://google.com/history/optout
  
  Make sure it's disabled.
  
  Also there seems to have been an update of some sort on Jan 8th & 9th
  
  http://www.seroundtable.com/google-update-17935.html
  
  Could be the case?
• 
  Lewis Barrs: +Daniel Sanchez ; Checked on numerous different computers in different locations/ips. There was some form of update hitting around this time but this still seems strange to me when the top 8-10 sites drop 8 pages. This would tell me that all got smacked with penalties or something more sinister is going on.  ;
• 
  W.E. Jonk: From the expert panel in this weeks SEO Questions hangout on air on 01:29:28 into the YouTube video: https://dumbseoquestions.com/q/i_have_just_seen_the_entire_page_1_results_change_in_one_go