Subject omission is gendered in English and Swedish

My student, Helen Pettersson, recently completed her MA dissertation on null subjects in English and Swedish text messages. She constructed some fake Whatsapp conversations, presented them to participants online, and asked for their judgements on various types of sentence. She wanted to know whether Swedish behaves like English in its acceptance of null subjects in colloquial registers, and as a sub-question, whether text messages are more like spoken English or like the more elliptical 'diary' register (things like Saw self in mirror today. Felt was growing fatter, which is OK in a diary but not in speech). Well, spoilers, in all the contexts she tested, English and Swedish are quite similar. But there was one way in which they differ, and it wasn't the topic of her dissertation but it is quite interesting.

Some of her stimuli presented a message with no prior context (it wasn't a reply to another text message) and asked her respondents what they thought the missing pronoun was: was it I, you, he, she, it, we, you (plural) or they? These were sentences like Might watch a film later. We expected that the majority of people would choose I, because that's what we know null subjects most commonly refer to in English, probably because it's the most accessible referent (you're more likely to be talking about yourself than someone else). But we also thought that there would be some variation, as it's perfectly possible that it could refer to someone else.

Here are the results for Swedish:

Mostly I (jag), as expected, with a smattering of the others, mostly He and She. Funnily enough, there are quite a few more participants who went with he when the sentence was about having broken a mirror - perhaps because boys are clumsy? 

And here are the results for English: 

There are lots more votes for they than in the Swedish data, and I wonder if this is because people were allowing it to be singular they, as in the pronoun used when it's an unspecified person involved with no known gender or possibly even number, as well as the third person plural pronoun. But in addition, just look at how many more votes the masculine pronoun got than the feminine! This is really a striking difference from Swedish, and I'm not aware of any particular reason for this, which makes it all the more intriguing.