Why Twitter Is Like a Thermometer

Twenty-plus years have passed since my graduate school days, and memory fades. But I clearly remember some basic definitions from semiotics.

There are three kinds of signs:

• Icon
• Index
• Symbol

Icons are visually related in a direct way to what they represent, while symbols have no obvious visual relation (for example, words). Indexes, though -- those were the trickiest ones to understand or explain. An index has a direct but not iconic connection to the signified concept. The examples that were commonly given were a thermometer, whose mercury physically moves in response to temperature to signify the degrees, or a set of footprints in a snowy field, signifying the passage of someone.

Twitter is an index of political events.


On Wednesday, June 26, when I got up for the day in Germany, it was 1:00 a.m. Central Time. I had been treating Twitter as my daily paper during the trip, so I fired it up on my phone as I got breakfast. When I refreshed the feed, there were so many tweets it had to be reloaded six times.

Uh oh, I thought, something happened overnight.

That something was the Wendy Davis filibuster in Austin, Texas. As Davis stood and spoke to delay the bill while day turned into evening, Twitter began to take notice. The live video feed of the session was linked repeatedly, and the number of people watching and commenting grew.

I was looking at all of this after the session had ended, but before the dust had settled. I read through the running comments as if they were in real time. Play-by-play comments dominated, but they were interspersed with others like:

• I can't believe this isn't on any of the 24-hour news networks.
• They're talking about Paula Deen instead of Wendy Davis on CNN.
• What is the point of 24-hour news if you're not going to cover breaking news?
• Now they're discussing low-calorie muffins on CNN.
• The mainstream media is dead.

Then the session ended and the Associated Press tweeted that the bill had passed, based on the word of the (Republican) lieutenant governor. Twitter was having none of that, and multiple people produced screen snapshots of the official Texas Senate website, showing the passage date as 6/26 -- and then second screen shots when it was back-dated to 6/25 instead. A little while later the Republicans acknowledged the vote had taken place after midnight.

I watched the search for the Boston Marathon bombers in a similar way, and Twitter repeats this pattern whenever there's a prominent event that takes place over time. On Wednesday morning I realized there was something familiar about it, and now I know why. It's an index, just as much as the mercury in a thermometer.