Question: **Is there any evidence which shows whether users are more able to recognise another user's Photo over their Username or vice versa?**

I am interested in understanding this from a usability perspective.

Lets say on a site such as this network, a user has both a username as well as a photo/avatar.

* On *Sci-Fi.se* [DVK](https://scifi.stackexchange.com/users/976/dvk) has a very recognisable **avatar**
* On *StackOverflow.se* [Jon Skeet](https://stackoverflow.com/users/22656/jon-skeet) has a very memorable **username**

Which of these is more recognisable/memorable?1

i.e. If **DVK** was to change his picture2, would this throw users off (not quickly recognising who the post if from) or would there be more of an issue if **Jon Skeet** changed his username?3

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**1.** Lets ignore rep points, as it is not relevant to my question.  

**2.** The caveat here is that 'DVK' is also a memorable username, but for the sake of this example lets ignore that.  

**3. Please reference research where possible.**

Answer: 
It depends not only on person, but also on service.

if you need to type username often ( or see it in your message ) then username is more memorable ( twitter )

Making avatar very small also prevent avatar to recognition.

Some services might allow to use not only latin letters in the username which make them weird 

Speaking about weird. It also depends on chosen username and avatar.

Long username is hard to memorize, photo of user face in an avatar 32x32 is hard to remember or recognize

As a conclusion very depends on service where both of their are going to be used.
Certain avatar images are very memorable and distinct. Some are almost indistinguishable. Likewise with user names. Someone who was asked to remember the username of "Jon Skeet" and was asked a day later later to identify it from a list of the ten most similar usernames might have a good chance at identifying it, while someone who was shown a generic gravatar and asked to identify it from a list including nine randomly-selected ones would have a relatively poor chance even five minutes later. On the other hand, someone asked to remember a username written in an unfamiliar script [e.g. a hypothetical user "絕對沒有"] would have a hard time than someone asked to remember the gravatar of Jon Skeet (sompared with the ten most similar gravatars, assuming nobody copied Mr. Skeet's picture). The differences in memorability between different usernames and avatars would seem to outweigh any general advantage usernames would have over avatars or vice versa. Incidentally, without looking back at the previous hypothetical username, can one one remember whether it was "絕對伏特加", "絕對沒有", or "絕對值" [Chinese characters from Google translate]