Effects of the discriminability of alternatives in three-alternative concurrent-schedule performance

Six pigeons were trained on two- and three-alternative concurrent schedules in which the alternatives were signaled by different wavelengths of light on the main pecking key. The schedules were arranged according to a switching-key procedure in which pecks on a white side key produced a 3-s blackout and, intermittently, a change in the variable-interval schedule of food programmed on the main (center) key after the blackout. In Part 1, a two-alternative concurrent variable-interval schedule was arranged in which the alternatives were signaled by 560 nm and 630 nm. Parts 2 and 3 arranged three-alternative concurrent variable-interval schedules with the alternatives signaled by 560 nm, 600 nm, and 630 nm (Part 2) and 560 nm, 623 nm, and 630 nm (Part 3). Within each part, the relative rate of food reinforcers available on the alternatives was varied across a wide range. In all parts of the experiment, the ratios of responses emitted between pairs of alternatives were more extreme than the ratios of reinforcers obtained on the pairs of alternatives, a result termed overmatching. In Parts 2 and 3, generalized matching sensitivities between pairs of alternatives were found to be higher when the reinforcer rate on the third alternative was low than when it was high—an apparent failure of the constant-ratio rule. The data were well described by an extension of the Davison and Jenkins (1985) model, which assumes differing discriminabilities between concurrent-schedule alternatives in combination with a punishing effect of blackout following changeovers.     

Dimensions of the Mysticism Scale: Confirming the Three-Factor Structure in the United States and Iran

In a mostly Christian American sample (N = 1,379), confirmatory factor analysis of Hood's (1975) Mysticism Scale verified the existence of Stace's (1960) introvertive and extrovertive dimensions of mystical phenomenology along with a separate interpretation factor. A second study confirmed the presence of these three factors in not only another group of Americans (N = 188), but also in a sample of Iranian Muslims (N = 185). Relationships of the introvertive and extrovertive factors with the interpretation factor were essentially identical across these two cultures, but the Americans displayed a stronger association between the two phenomenology factors. In both samples, the interpretation factor correlated positively with an intrinsic and negatively with an extrinsic religious orientation, and the introvertive factor predicted psychological dysfunction. Associations of the interpretation factor with relative mental health appeared only in the Iranians. These data offered general support for Stace's phenomenology of mysticism, although the ineffability he linked with interpretation proved to be as much or even more a feature of the introvertive experience, as hypothesized by Hood.     

Control by past and present stimuli depends on the discriminated reinforcer differential

The extent to which a stimulus exerts control over behavior depends largely on its informativeness. However, when reinforcers have discriminative properties, they often exert less control over behavior than do other less reliable stimuli such as elapsed time. We investigated why less reliable cues in the present often overshadow stimulus control by more reliable cues presented in the recent past, by manipulating the reliability and duration of stimulus presentations. Five pigeons worked on a modified concurrent schedule in which the location of the response that produced the last reinforcer was a discriminative stimulus for the likely time and location of the next reinforcer. In some conditions, either the location of the previous reinforcer, or the location of the next reinforcer, was signaled by a red key light. This stimulus was either Brief, occurring for 10 s starting a fixed time after the most recent reinforcer, or Extended, being present at all times between food deliveries. Brief and Extended stimuli that signaled the same information had a similar effect on choice when they were present, but control by Brief stimuli weakened as time since stimulus offset elapsed. Control was divided among stimuli in the present and recent past according to the apparent reliability of the information signaled about the next reinforcer. More reliable stimuli in the present degraded, but did not erase, control by less reliable stimuli presented in the recent past. Thus, we conclude that less reliable stimuli in the present control behavior to a greater degree than do more reliable stimuli in the recent past because these more reliable stimuli are forgotten, and hence their relation to the likely availability of food cannot be discriminated.     

Being there on time: Reinforcer effects on timing and locating

In research on timing, reinforcers often are assumed to influence discrimination of elapsed time. We asked whether changes in choice used to measure timing arise because of joint control by elapsed time and reinforcers, rather than from the direct modification of control by elapsed time by reinforcers. Pigeons worked on a concurrent-choice task in which 1 response was 9 times more likely to produce a reinforcer, reversing between locations when 19 s had elapsed since the marker event. Across conditions, we manipulated the percentage of reinforcers arranged before the probability reversal from 5 to 95%. These changes in reinforcer percentages altered control by location-based elements of the contingency, but not by time-based elements. Choice was well described by a model that assumes that control by the contingency is weakened by generalization across the time and location of reinforcers, and that these generalizations become more likely at later times since a marker. These findings add to a growing body of research that suggests that reinforcers share the same function as other environmental events in determining how the environment controls behavior.     

The role of identity in how whole‐blood donors reflect on and construct their future as a plasma donor

In the context of decreased demand for whole blood and increased demand for plasma‐derived products, donors in Australia are increasingly being asked to convert from whole‐blood to plasmapheresis donations. Plasmapheresis is a different type of donation to whole blood as the process takes longer and can be engaged in more frequently. What is unknown is whether whole‐blood donors view donating plasma as consistent with their donor identity and how they respond to the possibility of donating more frequently. To explore this, we undertook semistructured telephone interviews with 26 whole‐blood donors who had recently made their first plasma donation. Findings indicated that whereas donating plasma was viewed as a bigger ask than donating whole blood, the former was viewed as consistent with their identity as a donor because both behaviours were seen to benefit others and self and were located within the same institutional context. Donating plasma was an opportunity for donors to enhance their self‐concept as an altruistic giver. When contemplating their future donation behaviour, donors considered how their donor identity would fit alongside other salient roles. These findings have implications for how institutions can position their request of existing donors to give a different gift.     

Patterns in Father Presence and Engagement in Mongolia: A Historical Cross-Sectional Study

Journal of Child and Family Studies - Many households in Mongolia are facing increased livelihood and financial insecurity due to rapid social, economic, political, and climate changes. There is...