Abstract
Twenty younger and older adults participated in two experiments that evaluated their ability to visually discriminate lengths. Over the past century, some investigators have required participants to judge test stimuli relative to a single implicit standard (i.e., have used the method of single stimuli). In the current experiments, we not only asked participants to compare lengths relative to a single implicit standard, but to two implicit standards simultaneously. Performance for this latter task has never previously been investigated. The primary purpose of the experiments was to determine whether human adults (of any age) can effectively learn, remember, and utilize two implicit standards within a single block of experimental trials. The results demonstrated that while human adults can accurately discriminate test lengths relative to a single implicit standard, they cannot accurately discriminate lengths relative to two implicit standards simultaneously. Under these conditions, significant and large biases emerge. In addition, the discriminations become less precise. Human adults cannot effectively learn, remember, or utilize two implicit standards simultaneously. The results of the current study document a fundamental limitation in human visual memory. We also found (unlike other visual tasks) that increases in age do not adversely affect the ability to visually discriminate lengths relative to implicit standards.
Meeting abstract presented at VSS 2014