Contributions to measuring three psychophysical attributes: Testing behavioral axioms for loudness, response time as an independent variable, and attentional intensity
1. The research presented is an empirical evaluation of R. D. Luce's (2002a) “A psychophysical theory of intensity proportions, joint presentations, and matches.” The theory deals with the global percept of subjective intensity in which Luce proposes a psychophysical function ψ that maps a physical domain onto the positive reals. A number of testable behavioral properties are shown to lead to specific representations of the several primitives of the theory. In a series of experiments, most of these properties are subjected to an empirical evaluation—including all of those critical to the representations. The testing strategy is carried out in the auditory domain and concerns the subjective perception of loudness.
2. Response time is regarded as inherently a dependent variable as no known method exists by which a person can be instructed to respond at a precise speed to a given stimulus. However, a well established inverse relationship obtains between response times and stimulus intensity. Hence, it may be possible to determine the stimulus intensity that gives rise to a fixed median response time-or any fixed percentile. In this sense, response time can be treated as an independent variable. A proposed method employs adaptive techniques to estimate this intensity for a fixed response time and percentile. The idea is presented formally and an empirical method is evaluated using both extensive computer simulations and a simple empirical situation.
3. A prediction is developed and tested for the “Triangular circuit account of attention” model (D. LaBerge, 2000). The model is shown to predict an increase in attentional switching time for attention to location for tasks of low vs. high attentional demand. Using a classic cued-location paradigm, LaBerge and Buchsbaum (1990) and Liotti et al. (1994) conducted a series of attention experiments while measuring brain activity. The data revealed a significant increase in neural activity in brain areas associated with attention when the task is made more difficult. Three experiments based on these tasks are reported. The experiments include novel design elements to control for response biases and address, in addition to attention to location, attention to shape and issues of eye-movements.
0633: Cognitive therapy