[674 



II Wlilii )i ik I .1 1'FIN.SInI OCY 



NEUROPHYSIOLOGY III 



the standardized methodology developed by 1 lalstead 

 over the past 20 years at the University of Chicago, 

 are in agreement that his index provides a reliable 

 and sensitive indicator of brain lesions in man. There 

 is --till substantial disagreement as to whether the 

 principle of maw action (Lashley) applies throughout 

 the cerebral cortex in relation to biological intel- 

 ligence. Halstead has organized the 10 separate indi- 

 cators which comprise his measures of biological 

 intelligence into the testing console shown in figure 4. 

 With the help of a trained technician working in a 

 suitable environment, the testing apparatus makes 

 possible the presentation of approximately 5,000 con- 

 trolled stimuli through the modalities of vision, hear- 

 ing and sense of touch. The stimuli are programed in 

 such manner that the level of organization (starting 

 from simple discriminations to complex organization) 

 of stimuli can be specified from the objective responses 

 of the individual subject. All interpretations are done 

 by a third party without sensory contact with the 

 subject or without prior knowledge of the medical 

 history. The components of the Halstead Battery of 

 Tests consists of a category test (with instantaneous 

 auditory reinforcement of correct and incorrect re- 

 sponses); a tactual form-board test (which is never 

 experienced visually by the subject); a test for critical 

 fusion frequency; a test for auditory flutter-fusion fre- 

 quency (frequency of interruption at which bursts of 

 white noise fuse subjectively into continuous noise); a 

 speech perception test, a rate of tapping test; and a 

 time-sense memory test (repealed setting of an electric 

 clock with and without the aid of vision). In develop- 

 ing these indicators as measures of biological intelli- 

 gence, Halstead has studied their performance in a) 

 hundreds of neurosurgical cases; h) several hundred 

 normal controls including subgroups matched for age, 

 sex, E.Q., amount of formal education, occupational 

 level and ethnic origin, 1 ) normal young men tempo- 

 rarily under the stress of low-oxvgen environment or 

 simulated high altitude, <h psychiatric patients falling 

 in various diagnostic categories including schizophre- 

 nia; and e) other (lasses 1.1 patients including individ- 

 uals with acute or chronic metabolic or vascular dis- 

 eases Factor analyses and analyses of variance oi 

 relevant groups have been made as independent checks 

 on tip fat toi isolated ami identified in the above pro- 

 . 1 dures I lie resulting four fai toi model ol biologii .il 

 intelligence deserves the serious attention ol neuro- 



physiologistS and neuroc hemists as a possible clue In 



the replication 01 redundancy ol organized elements 

 which in. iv be characteristit ol cortical mechanisms. 

 I 01 purposes ol description and prediction, the 



variance on this battcrv of tests is grouped under such 

 headings as "judgment" (ability to organize recurrent 

 elements into principles or categories), 'power' (the 

 tonic energy or 'arousal' of the cortex), 'memory' (for 

 over-all organization and form as well as for the 

 details of place and relationship), and 'modality 1 

 (organized avenues of input and output for cortical 

 information 1. 



It is of interest that the yardstick or scale for bio- 

 logical intelligence is proving in various investigations 

 to be relatively 'culture-free' and appears to bear 

 directly upon the over-all adaptations of individuals 

 involved in intellectuallv creative work. 



NATURE OF IMAGES 



Plato was one of the first to note that the memory or 

 image of an object looks just like the original object. 

 In tgio Perky (49) presented experimental evidence 

 for this view. Her subjects were asked to imagine a 

 series of individual objects as if seen on a screen. Un- 

 known to the subject, an assistant projected an actual 

 picture of the particular object very faintly onto the 

 same spot on the screen. Twenty-seven adult ob- 

 servers mistook the faintly projected picture for their 

 own images. 



Normally, images or traces are less vivid or bright, 

 less saturated, less intense and somewhat simplified as 

 to content in comparison with percepts of real ob- 

 jects (",7). Vet drugs such as mescaline, for example, 

 can enhance the properties of the image to the point 

 where confusion with actual percepts arises (as noted 

 by Kluxer I. 



Figural , Iftereffects 



Prolonged inspection of a curved line, a bounded 

 area or a patch of color produces aftereffects which 

 distort the resulting trace in characteristic ways. For 

 example, following prolonged inspection of a curved 

 line, a straight line will be perceived as curved in the 

 opposite direction, a bounded area appears smaller, a 

 constant area recedes in space, a colored patch less 

 saturated ( ; -;, 34). This effect may last lor several 

 minutes, hours or davs. The aftereffect or overriding 

 of subsequent percepts has been attributed to satiation, 

 the 11. Utile of which remains obscure. It does appear 

 to be a property of the neiii.il pool which exerts its 

 influence without the subject being aware of its 

 presence (48), Its possible relation to after-discharge 

 in brain wave activilv is unknown. 



