Social and cognitive processes in interpersonal communication: implications for advanced telecommunications technologies.

Interactive multimedia conferencing systems, in which two or more remotely located people can work on cooperative tasks through shared audio, video, and data, appear to be the wave of the future. However, because of great advances in the underlying technology of multimedia conferencing systems, many design decisions have been driven by what is technically feasible as opposed to what will best suit the needs of the users. In this paper we provide a framework for the design and evaluation of features in advanced telecommunications products and services which is derived from empirical research on interpersonal communication. We also discuss implications of this research for the development and use of advanced telecommunications technologies.

The time-course of multiplicative and subtractive adaptation process.

This paper examines, for foveal cone vision, the processes which mediate the transition to a steady state of adaptation following a change of illumination. In the steady state, the signal from an adapting field is attenuated not only by a multiplicative factor (reduction in gain) but also by a subtractive signal. We show that the multiplicative change is accomplished very rapidly following the onset of an adapting field (within about 50 msec). Much of the subtractive change is also accomplished rapidly, but it takes several sec to complete. At the offset of the field, the multiplicative process takes over 200 msec to recover. This slower time-course at offset may be a consequence of receptoral persistence.

The response range of the blue-cone pathways: a source of vulnerability to disease.

Retinal disease preferentially affects the sensitivity of the "blue"-cone pathways. This vulnerability to disease may be due, in part, to a more limited response range. A psychophysical technique, the probe-flash paradigm, was used to test this hypothesis. The data suggest that the S-cone pathways have a more limited response range than the L-cone pathways. Explanations for blue-cone vulnerability are discessed in the context of this finding.

Interactions between rod and cone channels above threshold: a test of various models.

Brightness-matching and magnitude estimation data were obtained to test alternative explanations of the rod-cone interaction above threshold. Steady adapting fields were selected such that 500 and 640 nm test flashes presented in the parafovea stimulated largely the rod and cone systems, respectively. In the brightness-matching experiment stimuli of combined 500 and 640 nm light were matched to a white foveal standard flash set at various levels above threshold. Similarly, in the magnitude estimation experiment, brightness estimates were obtained for single 500 and 640 nm flashes as well as for super-imposed combination flashes. Combination stimuli appeared brighter than their individual components. Overall, the results suggest that rod and cone signals elicited by a single flash combine in an excitatory fashion; there is no evidence for rod-cone inhibition in this study. Further, the results for the suprathreshold and threshold conditions are qualitatively similar. The signals from the rod and cone systems combine less well than signals within a system but to a greater degree than predicted by probability summations or vector addition models.