Response-cost punishment with pigeons: Further evidence of response suppression via token loss

Four pigeons responded on a two-component multiple token-reinforcement schedule, in which tokens were produced according to a random-interval 30-sec schedule and exchanged according to a variable-ratio 4 schedule in both components. To assess the effects of contingent token loss, tokens were removed after every second response (i.e., fixed-ratio 2 loss) in one of the components. Response rates were selectively lower in the loss components relative to baseline (no-loss) conditions, as well as to the within-condition no-loss components. Response rates were decreased to a greater degree in the presence of tokens than in their absence. To control for the effects of changes in the density of token and food reinforcement, two parts consisted of additional conditions where food density and token loss were yoked to those in a previous loss condition. In the yoked-food condition, tokens were produced as usual in both components, but the overall density of food reinforcement in one of the components was yoked to that obtained during a previous token-loss condition. In the yoked token-loss condition, tokens were removed during one component of the multiple schedule at a rate that approximately matched the obtained rate of loss from a previous token-loss condition. Response rates in these yoked components were less affected than those in comparable loss components, despite similar densities of token, exchange, and food reinforcement. On the whole, the results support the conclusion that contingent token loss serves as an effective punisher with pigeons.     

Pyramid Linear Prediction Coding for Images

lintroductionCompressionofdigitalimagesandvideosignalstoreducetheirstorageandtransmissionbandwidthrequirementsisofgreatinterestintheimplementationofcolnnlunicationsystems.Moreandmorecompressioncodingmethod$fordigitalimagesandvideosignalshavebeenproposedto…     

Approaches to Study of Distance Education Students

The'Approaches to Studying'inventory of Ramsden and Entwistle (1981) was administered to groups of external and internal students at Capricornia Institute and the Tasmanian College of Advanced Education. Factor analysis revealed a similar factor structure for external students to that of the total sample. This finding, together with analysis of variance data, is taken as evidence that it is valid to use the inventory and the associated theories on learning styles with distance education students. Analysis of variance data showed differences in learning styles for older students. The implications of this finding for the design of distance education courses are discussed.     

Possible role of confounded taste stimuli in conditioned taste aversions

In many publications, Sjödén, Archer, and their colleagues have studied conditioned taste aversions and found that in addition to taste, the bottle and/or spout containing a solution exerts strong control over the expression of an aversion. For example, Sjödén and Archer claim that this bottle stimulus will support a bottle-illness association even with long delays between the bottle and illness and after only a single conditioning trial. They have interpreted their results as indicating that contextual effects are important in taste-aversion learning. However, a confound in their procedure, stemming from the bottles they used, could explain their results in a simple way. Sjödén and Archer have emphasized that the bottle stimuli they used to distinguish between contexts consisted of one of two different sizes of drinking spouts, the larger of which made a clicking noise when licked. However, the larger spouts were always attached to plastic bottles and the smaller spouts were always attached to glass bottles. If discriminable tastes from the plastic bottles existed, then taste may have been inadvertently manipulated. Support for the likelihood of a plastic taste includes the seminal work on taste-aversion learning that stemmed from the serendipitous use of plastic bottles in the cage that rats were irradiated in and glass bottles in the home cages (see Garcia, McGowan, & Green, 1972). In these early demonstrations, rats learned to avoid the taste of water in the plastic bottles but not the taste of water in the glass bottles.     

Changing practices: influences on classroom assessment

The pedagogical potential of classroom assessment to support student learning has increasingly been evidenced in research over the past decade. Constructive classroom assessment has been championed by assessment specialists, and endorsed by professional organizations. In practice, however, the process of changing classroom assessment from its traditionally summative orientation is not straightforward. This methodical review looks at how six sources, which are educational research, evaluative inquiry, large‐scale assessment, educational policy, professional development, and teachers’ beliefs, influence and mediate assessment practices. A group of purposively selected research articles are analysed as evidence of the dynamics in this complex process. Cross‐currents relating to research perspective, collaboration, and time are discussed. For the movement seen in this study to continue, the tension between teacher autonomy and school community, and the relationship between collective commitment and assessment literacy should be considered.     

The Consistency and Concomitants of Inhibition: Some of the Children, All of the Time

Toddlers displaying extremely inhibited behavior may be at risk for becoming socially withdrawn. However, behavioral inhibition may be a multifaceted characteristic, and its concurrent relation to toddler wariness with peers has not been examined. In this study, 108 toddlers (54 females) and their mothers were observed in novel situations involving unfamiliar settings, adults, and peers. Vagal tone, temperament, separation-reunion behavior, and maternal oversolicitousness also were assessed. There was little consistency of inhibited behavior across the 3 situations. Consistently inhibited toddlers had fearful temperaments, showed distress following maternal separation, and had mothers who were warm and controlling but unresponsive to children's cues during interaction. Toddlers with highly fearful temperaments and highly oversolicitous mothers were the most inhibited across contexts.     

Intentionality as measured in the persistence and elaboration of communication by chimpanzees (Pan troglodytes)

In human infancy, 2 criteria for intentional communication are (a) persistence in and (b) elaboration of communication when initial attempts to communicate fail. Twenty-nine chimpanzees (Pan troglodytes) were presented with both desirable (a banana) and undesirable food (commercial primate chow). Three conditions were administered: (a) the banana was delivered (successful communication), (b) half of the banana was delivered (partially successful communication), and (c) the chow was delivered (failed communication). The chimpanzees exhibited persistence in and elaboration of their communication in every condition except when the banana was delivered. Thus, their communication was about a specific item, demonstrating that both intentionality and nonverbal reference are capacities shared by humans with our nearest living relatives, the great apes.