Difference threshold for stimulus length under simultaneous and nonsimultaneous viewing conditions

The present study was concerned with Weber’s Law as it is related to the discriminability of the lengths of lines. Experiments were conducted to investigate three questions: (I) Is Weber’s Law equally applicable to simultaneous and nonsimultaneous viewing conditions? (2) Is the relationship between the stimulus sizes and the values ofDLs described more adequately by the function proposed by Weber or a generalized Weber’s Law stated by Miller? and (3) Is Weber’s Law better approximated by proximal or distal size? It was demonstrated that the discriminability of the lengths of lines follows Weber’s Law under the nonsimultaneous viewing condition, but not under the simultaneous viewing condition. Under the nonsimultaneous viewing condition, it was noted that the generalized Weber’s Law as stated by Miller described the relationship between the DL and stimulus size significantly better than the function proposed by Weber. From the results pertaining to the third question, it was not possible to determine whether the proximal or the distal size follows Weber’s Law more closely.