Single-modality signal levels employed for individual subjects tested in each of the four experiments. Auditory levels are for detection of pure tones in 50–dB SPL broadband noise. Tactile levels are for detection of sinusoidal vibrations presented to the fingertip. Different symbols represent results obtained in different experiments. Some subjects participated in more than one experiment. Solid line indicates the average across subjects and experiments for each frequency. Error bars are 1 SEM.
Summary of results for the baseline condition in Experiments 1–3. Percent-correct scores for the individual subjects in each experiment are averaged across multiple repetitions per condition; number of repetitions varies by subject, and is equal to or greater than four per subject. AVG is an average across subjects and repetition in each experiment. White bars represent auditory-alone conditions, gray bars represent tactile-alone conditions, and black bars represent the baseline condition with auditory and tactile , simultaneous presentation. Error bars are 1 SEM.
Summary of results for Experiment 1 (3a), Experiment 2 (3b), and Experiment 3 (3c). Percent-correct scores are averaged across subjects and sessions. Scores are shown for -alone (white bars), -alone (light gray bars), and for combined conditions (dark gray bars). In Experiment 1, scores are shown as a function of auditory frequency with tactile . In Experiment 2, scores are shown as a function of tactile frequency with auditory . In Experiment 3, scores are shown as a function of frequency where . Error bars are 1 SEM.
Predicted vs observed values for the two models of integration, showing data for conditions in which the auditory and tactile frequencies are equal to one another. The top row (4a) represents the results of the Pythagorean sum model for the four equal-frequency conditions across experiments (from left to right: 50, 125, 250, and 400 Hz). The 250 Hz panel pools data across Experiments 1–3, while the remaining panels show data from Experiment 3. The bottom row (4b) represents the results of the algebraic sum model for the four equal-frequency conditions across experiments (from left to right: 50, 125, 250, and 400 Hz). The 250 Hz panel pools data across Experiments 1–3, while the remaining panels show data from Experiment 3. Results for each subject are delineated by shape (see legend) in each panel. Open symbols indicate that the observed value failed the chi-squared test and filled symbols indicate the observed value passed the chi-squared test.
Ratio of the observed values to the Predicted values for each of the three models averaged across subjects and repetitions of each experimental condition. (a) Ratios for Experiment 1, in which the tactile and the auditory frequency was varied between 125 and 2000 Hz. (b) Ratios for Experiment 2, in which the auditory and the tactile frequency was varied between 50 and 400 Hz. (c) Ratios for Experiment 3, in which the auditory and tactile frequencies were equal and covaried between 50 and 400 Hz. The horizontal bar on each graph indicates a ratio of 1.0 (i.e., values). The dark gray bars represent the optimal single channel model, the gray bars represent the Pythagorean sum model, and the light gray bars represent the Algebraic sum model. Error bars are 1 SEM.
% correct scores averaged across four subjects and four repetitions per condition. Scores are shown for auditory PTs alone (white bars), auditory NBN alone (light gray bars), and for combined (dark gray bars). Scores are shown as a function of auditory PT frequency with NBN centered at 250 Hz and bandwidth of 48 Hz. Error bars are 1 SEM.
Chi-squared tests: predicted vs observed. This table enumerates the number of observations that have passed/failed the chi-squared goodness of fit test for each of the three models (i.e., optimal single channel, Pythagorean sum, and algebraic sum).
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