Multitasking: Switching costs
Not studies: three non-peer-reviewed items, all three read in full at source: the APA press release of 5 August 2001, complete, via the Newswise archive; the Monitor on Psychology write-up of October 2001, complete, at apa.org/monitor/oct01/multitask; and the APA topic page on multitasking and switching costs, complete, at apa.org/topics/research/multitasking, footer-dated 20 March 2006. None carries a DOI, so this entry is keyed on the corporate author and year. The items: American Psychological Association (2001), press release titled Is Multitasking More Efficient? Shifting Mental Gears Costs Time, Especially When Shifting to Less Familiar Tasks, embargoed until 6 p.m. EDT, 5 August 2001; Smith, D. (2001), Multitasking undermines our efficiency, study suggests, Monitor on Psychology 32(9), October 2001; and American Psychological Association, Multitasking: Switching costs, topic page, created 2006. A press release, a membership-magazine article and a web topic page, none of them peer-reviewed and none of them a journal article. This is the whole origin of the second most repeated number in the trade, and it dissolves. The press release contains no percentage of anything. It reports four experiments with young adults (12, 36, 36 and 24 participants in turn) who switched between tasks such as solving math problems or classifying geometric objects. Its strongest quantitative statement is that activating a rule takes several tenths of a second, which can add up when people switch repeatedly, so multitasking may seem more efficient on the surface while taking more time in the end. Its one extrapolation stops at the road: about half a second lost to task switching for a driver using a cell phone. The Monitor piece also carries no percentage, again gives several tenths of a second as its strongest statement, and carries a counterweight the trade never repeats, from Meyer himself: he asks what causes interference between tasks in some cases but not others, and says that question must be answered carefully to tell the full story about multitasking and executive control. The same piece cites Schumacher and colleagues in Psychological Science 12(2) as finding that under special circumstances people can do two tasks at once with little interference, and that paper was not read. The 2006 topic page is the entire source of the figure. Its account of the 2001 paper carries no percentage and describes the effect as sometimes a few tenths of a second per switch. In the next sentence it says that Meyer has said even brief mental blocks created by shifting between tasks can cost as much as 40 percent of someone's productive time. That is an unsourced, undated, uncited remark attributed on a web page, with no interview, paper, talk or date given, and the page's own list of thirteen further-reading items contains nothing that would supply it. The APA does not present it as a finding but as something a researcher said. The circulated version also changes the scope: can cost as much as 40 per cent is an upper bound on a conditional, while multitasking reduces productivity by 40 per cent is a point estimate of a mean. Verdict: dissolves. No original source exists for the figure as a measured quantity, and no APA press release carrying it exists, searched and not found. Criticise the figure and the chain of citation, never Professor Meyer: an informal upper bound offered in conversation is not a claim he published, and the error lies in the twenty years of citation that hardened it into a statistic. Where we stopped: at the report that Meyer has said it. On the published record it cannot be traced further.
Not studies: three non-peer-reviewed items, all three read in full at source: the APA press release of 5 August 2001, complete, via the Newswise archive; the Monitor on Psychology write-up of October 2001, complete, at apa.org/monitor/oct01/multitask; and the APA topic page on multitasking and switching costs, complete, at apa.org/topics/research/multitasking, footer-dated 20 March 2006. None carries a DOI, so this entry is keyed on the corporate author and year. The items: American Psychological Association (2001), press release titled Is Multitasking More Efficient? Shifting Mental Gears Costs Time, Especially When Shifting to Less Familiar Tasks, embargoed until 6 p.m. EDT, 5 August 2001; Smith, D. (2001), Multitasking undermines our efficiency, study suggests, Monitor on Psychology 32(9), October 2001; and American Psychological Association, Multitasking: Switching costs, topic page, created 2006. A press release, a membership-magazine article and a web topic page, none of them peer-reviewed and none of them a journal article. This is the whole origin of the second most repeated number in the trade, and it dissolves. The press release contains no percentage of anything. It reports four experiments with young adults (12, 36, 36 and 24 participants in turn) who switched between tasks such as solving math problems or classifying geometric objects. Its strongest quantitative statement is that activating a rule takes several tenths of a second, which can add up when people switch repeatedly, so multitasking may seem more efficient on the surface while taking more time in the end. Its one extrapolation stops at the road: about half a second lost to task switching for a driver using a cell phone. The Monitor piece also carries no percentage, again gives several tenths of a second as its strongest statement, and carries a counterweight the trade never repeats, from Meyer himself: he asks what causes interference between tasks in some cases but not others, and says that question must be answered carefully to tell the full story about multitasking and executive control. The same piece cites Schumacher and colleagues in Psychological Science 12(2) as finding that under special circumstances people can do two tasks at once with little interference, and that paper was not read. The 2006 topic page is the entire source of the figure. Its account of the 2001 paper carries no percentage and describes the effect as sometimes a few tenths of a second per switch. In the next sentence it says that Meyer has said even brief mental blocks created by shifting between tasks can cost as much as 40 percent of someone's productive time. That is an unsourced, undated, uncited remark attributed on a web page, with no interview, paper, talk or date given, and the page's own list of thirteen further-reading items contains nothing that would supply it. The APA does not present it as a finding but as something a researcher said. The circulated version also changes the scope: can cost as much as 40 per cent is an upper bound on a conditional, while multitasking reduces productivity by 40 per cent is a point estimate of a mean. Verdict: dissolves. No original source exists for the figure as a measured quantity, and no APA press release carrying it exists, searched and not found. Criticise the figure and the chain of citation, never Professor Meyer: an informal upper bound offered in conversation is not a claim he published, and the error lies in the twenty years of citation that hardened it into a statistic. Where we stopped: at the report that Meyer has said it. On the published record it cannot be traced further.
Written from the nOT STUDIES. Three non-peer-reviewed items, ALL THREE READ IN FULL AT SOURCE: the APA press release of 5 August 2001 complete, via the Newswise archive; the Monitor on Psychology write-up of October 2001 complete, at apa.org/monitor/oct01/multitask; and the APA topic page 'Multitasking: Switching costs' complete, at apa.org/topics/research/multitasking, footer-dated 20 March 2006. None carries a DOI, so this entry is keyed on the corporate author and year.
What our sources record
Recorded when this source was checked, figures included, with page references and quotation marks removed.
apa.org/topics/research/multitasking, created 2006