J-integral values were determined directly from the measured orthogonal displacement fields surrounding a stably growing crack in 2024-0 and 5052-H32 aluminum alloy single-edge notched (SEN) and cruciform specimens of 0.8-mm thickness. These J values were then used to compute the crack-tip displacements associated with the Hutchinson-Rice-Rosengren (HRR) field. The displacement component as a result of the difference field in the simplified two-parameter J-Q or J-T ductile fracture theories was obtained by subtracting the HRR displacement from the measured crack-tip displacement. The slope of the log-log plots of the two orthogonal, difference-field displacement components varied irregularily with radial distance with no consistent second-order strain singularity. The results suggest that further analysis is necessary before the simplified J-Q theory can be used to analyze stable crack growth in thin plates.