Delay and number of food reinforcers: Effects on choice and latencies

Pigeons were given a choice between two identical-duration situations (terminal links of chain schedules). One terminal link of the choice pair provided two food deliveries, and the other provided five. The exact times of these food deliveries differed between the terminal links and were varied over conditions. A single response during the initial link gave immediate access to the corresponding terminal link. Forced trials, during which only one of the initial-link keys was lighted, were interspersed with choice trials during which both initial-link keys were lighted. Choice tended to favor whichever terminal link was correlated with the higher sum of the immediacies (i.e., the sum of the reciprocals of the delays to each of the reinforcers following the choice, with all delays measured from the choice). Latencies on forced trials and on choice trials also were related (negatively) to the sum of the immediacies. This correlation among response measures (choice and latencies) suggests that both measures are manifestations of the effect of conditioned reinforcement on response tendencies.     

Tethered insect flight: A system for automated data processing of behavioral events

Flight mills to which flying insects are tethered, and which allow measurement of locomotion in a circular path, are used to measure flight capability in terms of frequency, duration, velocity, and distance. Also, they are adaptable to measurement of physiological processes such as respiration and energy consumption. We describe a flight-mill system with floating magnets and Teflon® bearings in its rotor that minimize frictional drag. Rotation (of the mill rotor) is transduced by interruption of a light beam to a phototransistor, which produces a signal monitored by a specially constructed event recorder. The event recorder temporarily stores the data from each mill and then transmits them in proper format for permanent storage on seven-track magnetic tape. The system allows simultaneous data collection from 18 individual insects and provides a computerized interpretation of their performance. The result is an analysis of all the significant parameters of flight that can be derived by measuring duration, velocity, distance, and frequency.     

Self-compassion and verbal performance: Evidence for threat-buffering and implicit self-related thoughts

ABSTRACT

Threats to self-esteem can impair well-being directly, e.g., via negative affect, but also indirectly, by impacting performance in valued domains. The present study examined whether self-compassion buffered individuals’ academic task performance from the effects of a self-esteem threat. In addition, this study tested possible effects of self-compassion on implicitly measured self-related thoughts. Participants (N = 333) were randomly assigned to self-esteem threat or neutral conditions, and then either a self-compassion manipulation or an expressive writing (control) condition before completing a set of GRE analogy items. Threat impaired GRE performance in the expressive writing control condition, but not in the self-compassion condition. Moreover, self-compassion appeared to marginally impact implicit non-evaluative self-thoughts, but did not affect evaluative thoughts or implicit self-esteem. The results of this study suggest that self-compassion has benefits for performance and thereby well-being. Future research should further explore the effects of self-compassion on performance and refine understanding of implicit thoughts as possible mechanisms.     

Episodic representations support early semantic learning: evidence from midazolam induced amnesia

Current controversy exists regarding the role of episodic representations in the formation of long-term semantic memories. Using the drug midazolam to induce temporary amnesia we tested participants' memories for newly learned facts in a semantic cue condition or an episodic and semantic cue condition. Following midazolam administration, memory performance was superior in the episodic and semantic condition, suggesting early semantic learning is supported by episodic representations.     

Monocular discs in the occlusion zones of binocular surfaces do not have quantitative depth--a comparison with Panum's limiting case

Da Vinci stereopsis is defined as apparent depth seen in a monocular object laterally adjacent to a binocular surface in a position consistent with its occlusion by the other eye. It is widely regarded as a new form of quantitative stereopsis because the depth seen is quantitatively related to the lateral separation of the monocular element and the binocular surface (Nakayama and Shimojo 1990 Vision Research 30 1811-1825). This can be predicted on the basis that the more separated the monocular element is from the surface the greater its minimum depth behind the surface would have to be to account for its monocular occlusion. Supporting evidence, however, has used narrow bars as the monocular elements, raising the possibility that quantitative depth as a function of separation could be attributable to Panum's limiting case (double fusion) rather than to a new form of stereopsis. We compared the depth performance of monocular objects fusible with the edge of the surface in the contralateral eye (lines) and non-fusible objects (disks) and found that, although the fusible objects showed highly quantitative depth, the disks did not, appearing behind the surface to the same degree at all separations from it. These findings indicate that, although there is a crude sense of depth for discrete monocular objects placed in a valid position for uniocular occlusion, depth is not quantitative. They also indicate that Panum's limiting case is not, as has sometimes been claimed, itself a case of da Vinci stereopsis since fusibility is a critical factor for seeing quantitative depth in discrete monocular objects relative to a binocular surface.     

Visual acuity improvement following fading and feedback training—I. Comparison of myopic and emmetropic volunteers

18 myopes and 18 emmetropes were randomly assigned in pairs to either Fading and Feedback training or a no-treatment control condition. The emmetropes were fitted with plus lenses equivalent to the spherical correction of the paired myope to simulate myopic visual acuity. Extensive visual acuity measures were obtained pre- and post-training. Data analyses indicated significant increases in recognition visual acuity for trained subjects, compared to no-treatment controls. The myopia/emmetropia variable did not interact with training even though there were noticably greater increases in visual acuity for trained myopes compared to the other conditions. Resolution visual acuity did not change as a function of training. These data are discussed in terms of their implications for better understanding the mechanisms responsible for visual acuity increases following behavioural training.