10 (47)

id, winie the nuracclluiar fluid rcimimeU waccr*Ucprivcu.

.he rats cl ran k moro chan norma). Thcrcforc, Mook and Kozub dis thcmse)vcs must liousc a ncgativc fcodback mechanism for ,gic froni cach of thcse threc studios implics chat thrcc soparacc dback mcchanisms exisc—-one in thc mouch, one in che stornach,

lflucnces

•wailnbility, mcrnory of thc clnpscd tinrc sińce thc last drink, and torganismic mcchanisms of drinking bchavior. As co wacer avail-havior dcpends on thc amounc of water in thc animal’s cnviron-tubę for a laboratory animal, Toaccs, 1979). Aninials with waccr-icnts drink less than do animais with watcr-restricted cnviron-ary sińce chat last drink, Toates also found tiiar animais acquirc to drinking schcdules, irrcspcctivc of lcvels of bodily fluids and

portant environmentaI influence, or extraorganismic rr.cchanism, dor is taste (Pfaffmann, 1961, 1982). Purc water is castelcss; it thcre-' :ntivc valuc bcyond wacer rcplenishmcnt. When watcr is given a nking bchavior changcs in accordance with the incenrivc value of .3.shows a graph of thc incencivc valuc of four tastcs: sweet, sour, iphed ac various stimulus intensi.ties. Using castelcss water as a basc-icss), any taste is at least slightly plcasant ac very Iow stimulus inten-istantial incctisitics, sucrose-flavorcd (sweet) water is markcdly morę sccless watcr. Tarcic acid- (sour), salt-, and quinine- (bitccr) fiavorcd cccily morę unpleasant than castelcss watcr. If we wcrc to providc ir typcs of flavorcd wacer to expcrimcntal participants, drinking crtainly vary as a function of thc pleasantness of che water's taste. ors such as a sweet taste offer a high inccntivc value for drinking, ink cxccssively and somccimcs dangcrously, biologically spcaking ). Thus, drinking behavior occurs for cwo rcasons, noc just one: (1) ent, and (2) subjcctivc scnsations of plcasure.¹

HUNGER

: complcx regulatory motivc than is thirst. Loss of water instigates .•plcnishment satiates thirst. Hungcr, one mighc thcrcforc think, lical loss and rcplcnishment of food. Hungcr, howevcr, must be ootli shorc-tcrm and long-term rcgulatcd. Hungcr rcgulation, as we ceraction between shorc-tcrm proccsscs opcracing undcr homcostatic twccn taste and drinking hehavior is mado moro complicated by thc face that watcr ic pcrccption of thc taste of watcr. Water bccomes incrcasingly morę hcdonically pos-v») with incrcascd dcprivation, and water hecomes incrcasinyly rnorc hcdonically avcr* ion (Ucck, 1979).

Degree of Pleasantncss ofFour Differcnt Taste Solutions

Sour co: Pfollmam (19óO).

rcgulation (c.g., caloric intakc) and long-tcrm proccsscs opcratl.ng- under nietabolic rcgulation (c.g., mctabolism and faę cel Is). To complicate our picturci^ircjicr, l\ung'e'r and cating bchavior arc strongly affectcd by lcarningand-environt^(unNrtl1u&neis, so much in fact chat an undcrscanding of hungcr rcquircs both phyjslblogibally-baącd and cnvironmcntally-bascd modcls (Wcingartcn, H9.Ś5).    •>    '

PhysiologiealRcgulation    ,    *

Hungcr ariscs from both brain and pcriphcral (non-braiń) bodily cucs. The maj r brain hungcr cue is che latcral hypothalamus (LH).jDcIgado and -Anand (1953), f>* instancc, had rats eat chcir cypical daily rncal and thcn- eleccrically stimujatct^rly-ir latcral hypothalamic nucleus. Stimulation (of thcir Ud produecd cxrcnsivc o (ng bchavior, dcspitc thc fact thac cach animahhad just caton to saucty. J u>t .i> thc la u '"'I