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 on the person.

A bit of an extreme example, but a dyslexic for example might struggle telling apart John Skeet and Jonno Teeks, whereas a color-blind person might not be able to tell two people apart that have combinations of certain colors in their avatar.

In general though, avatars tend to offer a wider variety of options. You can use letters, words, colors, shapes, etc. whereas usernames can only do a certain amount of characters, mostly in a single color.

Then again, usernames are often unique, and people won't be able to change them.

Combining those characteristics: avatars serve as a great "first glance" recognition but aren't set in stone, whereas usernames are good for specifics and certainty.

So in general, **avatars are more recognizable, but less authoritative**.
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.