Hemispheric Lateralization of Signal Processing
In chapter 7 dealing with the viscerosensory stimulus to be applied, I discussed the “noninvasive” or nonexperimentalist approaches, which make use of periodically and naturally occurring visceral fluctuations and of the physiological visceral impulses provoked by them. Parallel to the admission of the limits and difficulties of applying “invasive” techniques in human experiments on the viscerosensory system (see pp. 76), inspired by the original approach of the Laceys (Lacey & Lacey, 1978), we started to use the very attractive and simple heartbeat detection technique. Of course we knew of the early attempts of Brener and Jones (1974) and McFarland (1975), but it was Whitehead, Drescher, Heiman, and Blackwell (1977) who convinced us to include the heartbeat detection trials among our human viscerosensory methods. This suggestion proved to be timely, since in the early 1980s we sought “noninvasive” human experimental techniques adequate to investigate the hemispheric preference problem. Earlier we were unsuccessful in tackling the issue in rat experiments on visceroception (Ádám, Bárdos, Hoffmann, & Nagy, 1977). Jones (1994), in his important review article on this methodology, listed 48 published experiments in the years between 1974 and 1989 and another 54 unpublished studies (abstracts and dissertations) in that span. Thus, it was clear that this rather unsophisticated trend had become highly popular among scientists, mostly psychologists. This popularity had and still has many benefits, such as several research teams working on the same or related problems and being able to exchange ideas and experiences, to control and reproduce each other’s data, and so forth. There are at the same time some disadvantages to being fashionable, such as a peculiar “blindness of criticism” (recall the overpopularized “memory transfer” trend in the late 1960s or the oversimplified “biofeedback” campaign in the 1970s). A lack of critical thinking is not foreign to some authors working in the field of heartbeat perception. Namely, the common view regards the latter as a kind of “visceral perception.” However, it is clear to physiologists, experimental psychologists, and cardiologists that this is, as much a somatic and auditive sensory event (we detect heartbeats, more closely the pulses of the large arteries during systoles, through skin and interstitial receptors and even through the noise of the arterial blood flow of the organ of Corti in the inner ear) as it is a viscerosensory phenomenon (afferent nerve bundles run from the atrial and ventricular heart receptors, from the nerve endings of the great arteries of the chest through the vagus and the glosso-pharyngeal to the medulla transmitting mechanical events of the systole). Of course, this essential circumstance did not hinder us in our decision to study signal processing during heartbeat detection, since, as discussed (pp. 100–101), all viscerosensory functions analyzed so far dealt with mixed, visceral and somatic messages and we raised the provocative question: does “pure” viscerosensory input exist at all?
KeywordsMirror Effect Hemispheric Lateralization Monocular Viewing Mirror Condition Hemispheric Activation
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