Correct sitting is not all about sitting up straight
Correct working posture
Always sit back and move your chair close to the desk to maintain contact between your back and the seat back to help support and maintain the inward curve of the lumbar spine.
This can easily be achieved by choosing a seat which has a forward tilt of 5°-15° thereby ensuring your hips are slightly higher than your knees.
Poor working posture
Do not perch on the front of your seat. Do not place your keyboard too far away. Instead move it closer to the front of the desk
Avoid incorrect slouching where the angle of the pelvis rotates backwards. This results in the loss of the inward curve in the lumbar spine, causing excessive strain on the lumbar discs.
You can slouch if you need to in an ergonomic chair
Balanced rocking pelvic tilt and adjustable floating chairs allow the user to release the whole seat and back into free float thereby allowing the user to lean back and 'slouch correctly' whilst the chair supports the user.
You must ensure that you remain in the correct position with bottom back and the chair back following the lumbar spine.
Do not be tempted to slide forwards as this will stop the natural inward curve of the lumbar spine.
Take care with synchro mechanisms whereby the "freefloat" feature allows the chair back to go past 90° resulting in the pelvis rotating backwards to reduce the curve of the lumbar spine.