( CNN ) -- This holiday season , it 's still shoes off and liquids out at airport security , but changes may be on the way to part of this routine , and agents will be watching much more than the contents of your carry-on . Passengers prepare for a security screening at Washington Dulles International Airport in Virginia . In the coming months , the government expects to revisit its rule for the amount of liquids that may be brought aboard planes , while boosting the number of behavior detection officers deployed at checkpoints across the country . More than 2,000 are already on the job , and the program is growing every day , said Christopher White , a spokesman for the Transportation Security Administration . `` What the officers are looking for are physiological signs that can not be manipulated that indicate stress , fear or deception , '' White said . `` We find bad people everyday with behavior detection officers . '' The specially trained agents , who work in teams , establish a baseline of behavior and then search for people who rise above that level , he added . The TSA has been taking steps to reduce stress for all travelers at security , such as adding special family lanes , to make it easier for the officers to spot passengers who are acting suspiciously . `` By calming the checkpoint down , it makes people with potential hostile intent really stand out , '' White said . `` If there 's a shark fin in a rough sea , it 's impossible to see . If there 's a shark fin in a lake , it 's very easy to see . '' The word on liquids . Meanwhile , new technology may help change a familiar part of the security screening process . By now , most air travelers know the government 's 3-1-1 rule for liquids and gels : Containers no larger than 3 ounces are allowed in carry-on luggage , provided they are packed into one quart-size clear plastic zip-top bag , with one bag allowed per person . Those restrictions could be eased next year with the help of advanced X-ray machines that can be upgraded with software , like computers , White said . `` Scientists at the national labs have been working to develop an algorithm to plug into the machines that would allow us to tell the difference between a bottle of Coke and a bottle of liquid explosives , '' he said . The TSA is planning to have 600 of the machines installed at airports across the country by the end of this year and may look at changes to the 3-1-1 rule in fall 2009 , White added . Coming much sooner : the expansion of the family lane program to every airport in the country starting Thursday . See where the nation 's busiest airports are » . The special lanes are designed to make security screening as smooth as possible for people traveling with children , passengers with special needs or anyone unfamiliar with security procedures , while improving wait times for other travelers . What 's not changing for the foreseeable future : taking your shoes off at security . Running them through the X-ray machine is simply the fastest way of ensuring there 's nothing hidden inside , White said . Preparation and planning . If you are flying this Thanksgiving , expect lots of company but fewer people than last year . The Air Transport Association of America predicts a 10 percent drop in the number of people traveling on U.S. airlines during the holiday , compared with the same time period in 2007 . `` Some of the capacity cuts that carriers put into place have finally taken effect , but also we do think that the economic downturn is finally taking a toll on consumer spending when it comes to travel , '' ATA spokeswoman Elizabeth Merida said . The trade association for U.S. airlines predicts that the busiest travel days of this Thanksgiving holiday will be Wednesday , November 26 ; Sunday , November 30 ; and Monday , December 1 , with planes 90 percent full on average on those dates . Airports across the country are gearing up for the travel rush . `` We are making a commitment that even during peak periods , the [ security ] line will not exceed 20 minutes , '' said Ben DeCosta , aviation general manager at Hartsfield-Jackson Atlanta International Airport in Georgia . The world 's busiest airport has spent more than $ 25 million on improvements , including 10 additional `` high-productivity , speedy '' security lanes for a total of 32 , he added . Hartsfield-Jackson also offers a number of queuing options for the more than 40,000 people who line up at its security checkpoints every day . `` Our line management segregates people by expertise and by preference , and it helps to speed everything up and to make people less anxious about the beginning of their trip , '' DeCosta said . Hartsfield-Jackson is also joining the growing number of U.S. airports with whole-body imagers at security checkpoints . The machines offer an alternative to pat-downs by officers . No matter what airport you 're passing through , be prepared , White said . `` If you 're ready for security with your boarding pass and your ID out , with your shoes and your coat off , and with your liquids out of the carry-on bag , your experience is going to be very good and very pleasant , '' he said . `` For passengers who are not ready , they not only slow down themselves , they slow down the entire checkpoint line . ''
Government 's 3-1-1 rule for liquids and gels could be eased next year . TSA aims to reduce travelers ' stress , making it easier to spot suspicious behavior . Taking shoes off at security expected to remain in place for the foreseeable future . Family lane program expands to every airport in the country starting Thursday .