Here also, misidentifications are probably the result of confusion over wing versus dominant type: 3w4 and 4w3. The primary difference between these types can be seen in their relationship with their emotional life. Threes tend to focus on task, on efficiency, on performance. Of course, Threes have feelings, but as much as possible, they put them on the backburner whenever there are things to get done—and with many Threes, that is most of the time. As Threes become less healthy, they increasingly see their own feelings as "speed bumps"–annoyances that must be dealt with but which interfere with their effectiveness. Threes want to get their goals accomplished, and then, time permitting, process their feelings.
Fours are almost the exact opposite. Naturally, Fours want to accomplish things too, but when difficult feelings arise, Fours want to stop what they are doing and process them before returning to their tasks. The less healthy the Four, the more he or she will need lots of time to sort through troubling feelings and reactions. Threes can see the Four's preoccupation with sorting feelings as unprofessional and immature. Fours can see the Three's obsession with performance as inauthentic and shallow.
It is far more common for Threes to mistype as Fours than vice versa. This is especially true for Threes who grew up in families in which artistic self-expression was particularly valued. They may mistakenly believe that only Fours are creative, while failing to recognize that there have been many noted artists who are Threes.