When? Not then!

Here's a pretty specific comment, though it's related to my empty phrases post of a couple of years ago.  I have noticed that students have a habit of starting a sentence with the word "When" in instances where the word does not apply.

The error occurs most commonly in a Results section of a lab report.  Here's an example:

When we looked at the data, the control group remembered twice as many words as the experimental group.

There are variations on this theme ("When looking at Figure 2...," "When a t-test was conducted...").  In the example quoted above, the control group remembered twice as many words as the experimental group.  When did they do this?  Not "when" the researchers "looked at the data", but rather "when" the experiment was conducted.

So the first sin in this sentence is that it's inaccurate.  Now let's make it accurate:

When the experiment was conducted, the control group remembered twice as many words as the experimental group.

Now it's accurate, but the second sin becomes apparent: that information is irrelevant.  Of course that's "when" the the groups did the remembering, but did you really think you had to tell me that?  Is there any possibility of misunderstanding this timing of events?  The answer is no - and so the entire clause becomes an "empty phrase" that lends no information to the sentence which isn't already strongly implied by the context.

In other cases, there's simply no "when" involved at all.  Imagine this comment relevant to an image comparing the brain sizes of several different primates:

When looking at the brain sizes of various primates (Figure 1), humans have a much larger brain proportionate to their body than their nearest relatives.

Again, the statement is inaccurate, since it implies that humans didn't have a larger proportionate brain size until someone looked at a figure.  But worse, it isn't even possible to rewrite the sentence using the word "when" that is in any way accurate.  The brain size phenomenon isn't a thing that occurred at some instant in time, it is a thing that is true of the world.

In many cases, the psychology experiments we conduct - even if they must obviously occur on some specific days on the calendar - are nonetheless attempting to describe things that are true of the world.  Thus, returning to the original example above, crafting a sentence using the word "when" at least tacitly implies that the result being described is limited to a particular moment in time.  If the "experimental group" was denied sleep for 48 hours, then hopefully the result of the experiment is teaching us a fact about the world - sleep deprivation is bad for memory - not just describing what happened to some participants at one instant in time that has no relevance to other people at other moments in time.  The word "when" trivializes the process.