Form stable cohesive silicone gel breast implants are firmer than earlier generation silicone gel implants. The implants don't change in firmness with positional changes, however. Typically, when a woman lies on her back, her breast tissue shifts off to the side. In some women, there is enough looseness of the breast that when it shifts toward the outside there is very little tissue left covering the front of the chest, while she is in that position. If she had a breast augmentation with a more firm breast implant, then while she was standing and the implant was more covered by the breast, the breast may overall feel fairly soft. But when she lies flat, the breast itself may shift over, while the implant may stay in more of a central position, and thus not be covered by as much breast tissue. This could give the perception that the breast or rather the implant feels more firm, even though the implant hasn't actually changed.