TASTE STIMULATION AND PREFERENCE BEHAVIOR 



271 



of intermittent reinforcement (variable intervals or ratios, depending on 

 the schedule). The smaller the volume and the less frequent the reinforce- 

 ment, the closer the rate functions tend to reflect sensory magnitudes 

 (Pfaffmann, 1960). Guttman's (1954) important study of bar pressing on 

 an intermittent reinforcement schedule showed that relative rates of 



350 



2 50 



i 



c 200 



D 



c '50 



3 

 O 



I 



00 



00 



50 



W/ 



2.3 -2.0 -1.7 



0.0 0.3 



Log 



iO 



Molar Cone. Sucrose 



Fig. 9. Attenuation of two bottle preference for sugar following ablation of 

 most of the thalamic gustatory relay. 



response to glucose and sucrose were the same as their relative sweetness 

 for man. The same relationship held for the relative taste effectiveness 

 for the rat's chorda tympani response for these two sugars (Hagstrom and 

 Pfaffmann, 1959). 



Collier (1961) has worked out the detailed parameters of reinforcement 

 in a bar pressing situation in terms of stimulus intensity, volume, and 

 interval between reinforcements. He concludes that three independent 

 sets of events control ingestive behavior : (a) the sensory properties of the 

 substance being ingested, (b) the physical properties of the momentary 

 post-ingestive load, perhaps a non-specific osmotic gastric factor, and 

 (c) nutritive condition of the organism. 



