Characteristics of Visual and Haptic Functions Relate Similarly to Alpha Rhythm Parameters

Visual short-term memory (STM) for digits and reaction times (RT) has been found to correlate significantly with parameters of the occipital background EEG: the dominating alpha frequency and the alpha spindle duration (Markina and Maltzeva, 1993 Proceedings of 7th EMPS in Trier pp 311 – 314). STM span is more closely related to the latter, RT to the former of these parameters. We studied how certain characteristics of accuracy in haptic performance correlated with the same alpha parameters. We measured the control of line-length scatter, and the quantity of metrically accurate copies, in the standard task of blindly copying zigzag lines. The two measures were statistically independent of each other. We found that these characteristics of haptic performance show a similar pattern of correlation with alpha parameters as do STM and RT. Line-length scatter, as an index of control processes in the motor system, is related to alpha spindle duration. The quantity of metrically accurate copies, as an index of how precisely external metrical parameters are mapped to a subjective representation, is related to the dominating alpha frequency. The results are supported by factor analysis. They imply that (1) there are similar types of structures in visual cognition and haptic processes, and (2) the alpha rhythm parameters considered underly both kinds of processes.