How do E and Z isomers affect conjugation?

Stereoisomers will also affect the p-orbitals and conjugations.

Figure 1: E and Z isomers

The E isomer is more favored for the structure in terms of steric hindrance and conjugation.

The Z isomer has two large groups too close together causing steric hindrance meaning it is less favored. The geometry around the double bond differs and hence does not participate in the conjugated system.