EMB ERJ 170/175 ER/LR
Flight Crew Air Transport Pilot (ATP)
Situational Awareness
Deviation / Discrepancy - Procedural Clearance; Ground Incursion Taxiway
Flight Crew Became Reoriented
Human Factors
From [the] gate [we were] instructed to hold short of RA and contact ground. Ground control's instructions were to taxi to 4L via B; RB; short of PA. After we were established on B we saw PA straight ahead and remembered our instructions to hold short of PA. We continued towards it and after missing our turn at RB; ground advised us that we had gone the wrong way.I believe having a Captain flying as an FO is a safety problem waiting to happen. While I cannot adequately explain here how this affected our situation; I do believe that it played a role. The taxiway layout in Newark is confusing.
ERJ-170 Captain reported deviating from assigned taxi route; and commented that it was unsafe to have a Captain acting as a First Officer.