We have measured the low-temperature transport properties of front-gated GaAs Al0.33Ga0.67As heterostructures. Collapse of spin-splitting and an enhanced Lande \g\-factor at Landau level filling factors both v = 3 and 1 are observed. Our experimental results show direct evidence that the electron-electron interactions are stronger at = 3 than those at I over approximately the same perpendicular magnetic field range. (C) 2002 Elsevier Science B.V. All rights reserved.