Sensitivity to sucrose in smokers and nonsmokers: A comparison of TSD and percent correct measures

Ten smokers and 10 nonsmokers were compared for taste sensitivity to sucrose on two discrimination tasks, one at near-threshold (NT) concentration level and one at suprathreshold (ST) concentration level. The data were analyzed using the d_s and area under ROC curve measures based on the theory of signal detection (TSD). and by using the percentage correct responses. Analysis of both TSD measures showed smokers to be significantly more sensitive than nonsmokers on the NT .task and more sensitive on the ST task, but not significantly so. Comparison of mean percent correct responses showed no significant differences. A reflexive enhancement phenomenon was suggested as a possible interpretation. A decreased sensitivity to the bitter taste in smokers apparently results in an increased sensitivity to the sweet taste.     

Behavioral techniques in the treatment of obesity: A comparative analysis

The relative efficacy of the major techniques typically used in behavioral treatment programs for weight reduction was investigated using obese adult volunteers. Study 1 compared the effects of self-monitoring, self-control procedures, monetary rewards, aversive imagery and relaxation training. These procedures resulted in significantly greater weight reduction than either a no treatment group or subjects who graphed and recorded daily weight. Self-monitoring of daily caloric intake was as effective as the other methods, both singly and combined, over a 4 week treatment period. Study 2 compared the long-term effects of self-monitoring vs the full complement of behavioral techniques used in Study 1. The full behavior management program was significantly more effective, both during the treatment period and at 3 and 12 week follow-ups, although self-monitoring again produced substantial weight loss.     

Verbal reaction times to hues vs hue names and forms vs form names

Iwo choice reaction time (RI) studies were carried out in which different classes of stimuli—hues vs hue names in one study and forms vs form names in the other—occurred in independent lists of2, 4, and6 equally probable alternatives. Mean choice RIs were faster for hue names and form names than for hues and forms with4 and6 alternatives, but no significant differences were found in the2-stimulus lists. In both studies, significant list length by stimulus type (e.g., hues vs hue names) interactions indicated greater increase in mean RI with increases in list length for forms and hues than for form names and hue names. It was concluded that differential amounts of generalization of interference aceounted for the interactions. Effects of experimental variables on inferred components of RI were also examined.     

Visual signal detection and the locus of foreperiod effects

The effect of alertness on S's sensitivity to external signals was determined by varying the foreperiod in a visual signal detection task. Discriminability increased with increasing foreperiods up to an optimal foreperiod, beyond which it decreased slightly. This pattern of results parallels closely that of many foreperiod studies in which reaction time was the dependent variable. Because no speeded response was required in this signal detection task, it was concluded that alertness must be affecting an information processing stage prior to those associated with responding. Other evidence indicates that alertness does not affect sensory stages either. Alertness, by elimination, must be affecting the operation of a central stage, Posner's view of alertness which implicates the central stages is discussed.     

Sentence-type variables as aural concept formation dimensions

An aural conjunctive concept formation experiment used as stimuli sentences varying systematically in Voice (active/passive), Mood (declarative/interrogative), Modality (affirmative/negative), tense, and lexical content. Target classes were the eight sentence types defined by all combinations of the first three syntactic variables. Aural processing was more difficult than visual, but higher education level facilitated concept acquisition for males and females equally (cf. Bakeret al., 1973). The 64 undergraduate subjects tended to avoid syntactic analysis in depth, classifying sentences on as cursory a basis as the task allowed. The simple, unequivocal syntactic signals of Mood and Modality meaning were readily apparent, but the discrimination of Voice was complicated by ambiguous syntactosemantic associations and lack of discourse context. Voice is thus not seen as a determinant of utterance type, but as a context- and content-dependent realization of agent or object focus in transitive messages.This report is based on an M.Sc. thesis completed at the University of Alberta (Edmonton, Canada), in 1972     

Limits to preference and the sensitivity of choice to rate and amount of food

Studies of choice holding food‐amount ratio constant while varying food‐rate ratio within sessions showed that local changes in preference depend on relative amount of food. The present study investigated whether sensitivity of choice to food‐rate ratio and sensitivity to food‐amount ratio are independent of one another when food‐rate ratios are varied across sessions and food‐amount ratios are varied within sessions. Food deliveries for rats’ presses on the left and right levers were scheduled according to three different food‐rate ratios of 1:1, 9:1, and 1:9; each food‐rate ratio lasted for 106 sessions and was arranged independently of seven food‐amount ratios (7:1, 6:2, 5:3, 4:4, 3:5, 2:6, and 1:7 food pellets) occurring within sessions in random sequence. Each amount ratio lasted for 10 food deliveries and was separated from another by a 60‐s blackout. Sensitivity to rate ratio was high (1.0) across food deliveries. Sensitivity to amount ratio was low when food rates were equal across alternatives, but was high when rate ratio and amount ratio opposed one another. When rate ratio and amount ratio went in the same direction, choice ratio reached an elevenfold limit which reduced sensitivity to approximately zero. We conclude that three factors affect sensitivity to amount: (1) the limit to preference, (2) the equal effect on preference of amounts greater than four pellets, and (3) the absence of differential effects of switches in amount in the equal‐rates (1:1) condition. Taken together, these findings indicate that rate and amount only sometimes combine independently as additive variables to determine preference when amount ratios vary frequently within sessions.