criminal psychology-第54部分

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tter。　Therefore；　before　an　assertion　of　a　short…sighted　man　is　doubted　an　experiment　should　be　made；　or　at　least　another　trustworthy　short…sighted　person　should　be　asked　for　his　opinion。

The　background　of　objects；　their　movement　and　form　have　decided　effects　on　the　difference　in　visual　perception。　It　is　an　ancient　observation　that　lengthy　objects　like　poles；　wires；　etc。；　are　visible　at　incomparably　greater　distances　than；　e。　g。；　squares　of　the　same　length。　In　examination　it　has　been　shown　that　the　boundary　of　accurate　perception　can　hardly　be　determined。　I　know　a　place　where　under　favorable　illumination　taut；　white　and　very　thin　telephone　wires　may　be　seen　at　a　distance　of　more　than　a　kilometer。　And　this　demands　a　very　small　angle　of　vision。

Humboldt　calls　attention　to　the　large　number　of　‘‘optical　fables。''　He　assures　us　that　it　is　certainly　untrue　that　the　stars　may　be　seen　in　daylight　from　a　deep　well；　from　mines；　or　high　mountains；　although　this　has　been　repeatedly　affirmed　since　Aristotle。

The　explanation　of　our　power　to　see　very　thin；　long　objects　at　　a　very　great　distance；　is　not　our　affair；　but　is　of　importance　because　it　serves　to　explain　a　number　of　similar　phenomena　spoken　of　by　witnesses。　We　have　either　incorrectly　to　deny　things　we　do　not　understand；　or　we　have　to　accept　a　good　deal　that　is　deniable。　We　will　start；　therefore；　with　the　well…known　fact　that　a　point　seen　for　a　considerable　time　may　easily　disappear　from　perception。　This　has　been　studied　by　Helmholtz　and　others；　and　he　has　shown　how　difficult　it　is　to　keep　a　point　within　the　field　of　vision　for　only　ten　or　twenty　minutes。　Aubert　examines　older　studies　of　the　matter　and　concludes　that　this　disappearance　or　confusion　of　an　object　is　peripheral；　but　that　fixation　of　a　small　object　is　always　difficult。　If　we　fix　a　distant　point　it　is　disappearing　at　every　instant　so　that　an　accurate　perception　is　not　possible；　if　however　we　fix　upon　a　long；　thin　body；　e。　g。；　a　wire；　it　is　unnecessary　to　fix　a　single　point　and　we　may　see　the　object　with　a　wandering　eye；　hence　more　clearly。

Helmholtz　adds　that　weakly　objective　images　disappear　like　a　wet　spot　on　warm　tin；　at　the　moment　a　single　point　is　fixed；　as　does　e。　g。；　a　landscape　seen　at　night。　This　last　acute　observation　is　the　basis　of　many　a　testimony　concerning　the　sudden　disappearance　of　an　object　at　night。　It　has　helped　me　in　many　an　examination；　and　always　to　advantage。

In　this　connection　the　over…estimation　of　the　moon's　illuminating　power　is　not　to　be　forgotten。　According　to　Helmholtz　the　power　of　the　full　moon　is　not　more　than　that　of　a　candle　twelve　feet　away。　And　how　much　people　claim　to　have　seen　by　moonlight！　Dr。　Vincent＇1＇　says　that　a　man　may　be　recognized　during　the　first　quarter　at　from　two　to　six　meters；　at　full　moon　at　from　seven　to　ten　meters；　and　at　the　brightest　full　moon；　an　intimate　may　be　recognized　at　from　fifteen　to　sixteen　meters。　This　is　approximately　correct　and　indicates　how　much　moonlight　is　over…estimated。


＇1＇　Vincent：　Traitdecine　lgrand　du　Saule。


In　addition　to　the　natural　differences　of　sight　there　are　also　those　artificially　created。　How　much　we　may　help　ourselves　by　skilful　distinctions；　we　can　recognize　in　the　well…known　and　frequently…　mentioned　business　of　reading　a　confused　handwriting。　We　aim　to　weaken　our　sense…perception　in　favor　of　our　imagination；　i。　e。　so　to　reduce　the　clearness　of　the　former　as　to　be　able　to　test　upon　it　in　some　degree　a　larger　number　of　images。　We　hold　the　MS。　away　from　us；　look　at　it　askant；　with　contracted　eyebrows；　in　different　lights；　and　finally　we　read　it。　Again；　the　converse　occurs。　If　we　have　seen　something　with　a　magnifying　glass　we　later　recognize　　details　without　its　help。　Definite　conditions　may　bring　to　light　very　great　distinctions。　A　body　close　to　the　face　or　in　the　middle　distance　looks　different　according　as　one　eye　or　both　be　used　in　examining　it。　This　is　an　old　story　and　explains　the　queer　descriptions　we　receive　of　such　objects　as　weapons　and　the　like；　which　were　suddenly　held　before　the　face　of　the　deponent。　In　cases　of　murderous　assault　it　is　certain　that　most　uncanny　stories　are　told；　later　explained　by　fear　or　total　confusion　or　intentional　dishonesty；　but　really　to　be　explained　by　nothing　more　than　actual　optical　processes。

I　do　not　believe　that　binocular　vision　is　of　much　importance　in　the　law；　I　know　of　no　case　in　ordinary　vision　where　it　matters　whether　one　or　both　eyes　have　been　used。　It　is　correct　to　assert　that　one　side　or　the　other　of　a　vertically　held　hand　will　be　clearer　if；　before　looking　at　it　with　both　eyes；　you　look　at　it　with　one　or　the　other；　but　this　makes　little　difference　to　our　purpose。　It　must　be　maintained　that　a　part　of　what　we　see　is　seen　with　one　eye　only；if；　e。　g。；　I　look　at　the　sky　and　cover　one　eye　with　my　hand；　a　certain　portion　of　the　heaven　disappears；　but　I　observe　no　alteration　in　the　remaining　portion。　When　I　cover　the　other　eye；　other　stars　disappear。　Therefore；　in　binocular　vision　certain　things　are　seen　with　one　eye　only。　This　may　be　of　importance　when　an　effect　has　been　observed　first　with　both　eyes；　then　with　one；　raising　the　question　of　the　difference　in　observationbut　such　a　question　is　rare。

There　are　two　additional　things　to　consider。　The　first　is　the　problem　of　the　influence　of　custom　on　increasing　visual　power　in　darkness。　This　power　is　as　a　rule　undervalued。　No　animal；　naturally；　can　see　anything　in　complete　darkness。　But　it　is　almost　unbelievable　how　much　can　be　seen　with　a　very　little　light。　Here　again；　prisoners　tell　numerous　stories　concerning　their　vision　in　subterranean　prisons。　One　saw　so　well　as　to　be　able　to　throw　seven　needles　about　the　cell　and　then　to　find　them　again。　Another；　the　naturalist　Quatremologie。''　Aubert　tells　of　his　having　had　to　stay　in　a　room　so　dark　as　to　make　it　necessary　for　others　to　feel　their　way；　but　nevertheless　being　able　to　read　books　without　detection　because　the　others　could　not　see　the　books。

How　quickly　we　get　used　to　darkness　and　how　much　more　we　see　after　a　while；　is　well　known。　It　is　also　certain　that　the　longer　you　are　in　darkness　the　more　you　see。　You　see　more　at　the　end　of　a　day　than　after　a　few　hours；　and　at　the　end　of　a　year；　still　more。　The　　eye；　perhaps；　changes　in　some　degree　for　just　this　purpose。　But　a　prolonged　use　of　the　visual　mechanism　tends　to　hypertrophy　or　atrophy；　as　the　eyes　of　deep…sea　fishes　show。　It　is　well；　in　any　event；　to　be　careful　about　contradicting　the　testimonies　of　patients　who　have　long　lived　in　the　dark；　concerning　what　they　have　seen。　The　power　to　see　in　the　dark　is　so　various　that　without　examination；　much　injustice　may　be　done。　Some　people　see　almost　nothing　at　twilight；　others　see　at　night　as　well　as　cats。　And　in　court　these　differences　must　be　established　and　experimentally　verified。

The　second　important　element　is　the　innervation　of　the　muscles　in　consequence　of　movement　merely　seen。　So　Stricker　points　out；　that　the　sight　of　a　man　carrying　a　heavy　load　made　him　feel　tension　in　the　muscles　involved；　and　again；　when　he　saw　soldiers　exercising；　he　almost　was　compelled　openly　to　act　as　they。　In　every　case　the　muscular　innervation　followed　the　visual　stimulus。

This　may　sound　improbable　but；　nevertheless；　everybody　to　some　degree　does　the　identical　things。　And　at　law　the　fact　may　be　of　importance　in　cases　of　assault　and　battery。　Since　I　learned　it；　I　have　repeatedly　observed　in　such　cases；　from　harmless　assault　to　murder；　that　people；　although　they　had　not　been　seen　to　deal　any　blows；　were　often　accused　of　complicity　simply　because　they　were　making　suspicious　movements　that　led　to　the　following　inference：　‘‘They　stuck　their　hands　into　their　trousers　pocket　looking　for　a　knife；　clenched　their　fists；　looked　as　if　they　were　about　to　jump；　swung　their　hands。''　In　many　such　cases　it　appeared　that　the　suspects　were　harmless　spectators　who　were　simply　more　obvious　in　their　innervation　of　the　muscles　involved　in　the　assault　they　were　eagerly　witnessing。　This　fact　should　be　well　kept　in　mind；　it　may　relieve　many　an　innocent。


Section　38。　（2）　_Color　Vision_。

Concerning　color　vision　only　a　few　facts　will　be　mentioned：　1。　It　will　be　worth　while；　first　of　all；　to　consider　whether　color　exists。　Liebmann　holds　that　if　all　the　people　were　blind　to　red；　red　would　not　exist；　red；　i。　e。；　is　some　cervical　phantasy。　So　are　light；　sound；　warmth；　taste；　etc。　With　other　senses　we　have　another　world。　According　to　Helmholtz；　it　is　senseless　to　ask　whether　cinnabar　is　red　as　we　see　it　or　is　only　so　as　an　optical　illusion。　‘‘The　sensation　of　red　is　the　normal　reaction　of　normally　constructed　eyes　to　light　reflected　from　cinnabar。　A　person　blind　to　red；　will　see　cinnabar　as　black；　or　a　dark　grayish　yellow；　and　this　is　the　correct　reaction　　for　these　abnormal　eyes。　But　he　needs　to　know　that　his　eyes　are　different　from　those　of　other　people。　In　itself　the　sensation　is　neither　more　correct　nor　less　correct　than　any　other　even　though　those　who　can　see　red　are　in　the　great　majority。　The　red　color　of　cinnabar　exists　as　such　only　in　so　far　as　there　are　eyes　which　are　similar　to　those　of　the　majority　of　mankind。　As　such　light　reflected　from　cinnabar　may　not　properly　be　called　red；　it　is　red　only　for　especial　kinds　of　eyes。''　This　is　so　unconditionally　incorrect　that　an　impartial　judge　of　photography　says＇1＇　that　everything　that　normal　eyes　call　violet　and　blue；　is　very　bright；　and　everything　they　call　green　and　red　is　very　dark。　The　red…blind　person　will　see　as　equal　certain　natural　reds；　greens　and　gray…yellows；　both　in　intensity　and　shadow。　But　on　the　photograph　he　will　be　able　to　distinguish　the　differences　in　brightness　caused　by　these　three　otherwise　identical　colors。　We　may；　therefore；　assume　that　colors　possess　_*objective_　differences；　and　that　these　objective　differences　are　perceived　even　by　persons　of　normal　vision。　But　whether　I　am　able　to　sense　the　same　effect　in　red　that　another　senses；　and　whether　I　should　not　call　red　blue；　if　I　had　the　color…vision　of　another；　is　as　impossible　to　discover　as　it　is　useless