Context effects in a temporal discrimination task" further tests of the Scalar Expectancy Theory and Learning-to-Time models

Pigeons were trained on two temporal bisection tasks, which alternated every two sessions. In the first task, they learned to choose a red key after a 1-s signal and a green key after a 4-s signal; in the second task, they learned to choose a blue key after a 4-s signal and a yellow key after a 16-s signal. Then the pigeons were exposed to a series of test trials in order to contrast two timing models, Learning-to-Time (LeT) and Scalar Expectancy Theory (SET). The models made substantially different predictions particularly for the test trials in which the sample duration ranged from 1 s to 16 s and the choice keys were Green and Blue, the keys associated with the same 4-s samples: LeT predicted that preference for Green should increase with sample duration, a context effect, but SET predicted that preference for Green should not vary with sample duration. The results were consistent with LeT. The present study adds to the literature the finding that the context effect occurs even when the two basic discriminations are never combined in the same session.     

Interpretation and the Problem of Domination: Paul Ricoeur's Hermeneutics

Hermeneutics, or the science of interpretation,is well accepted in the humanities. In thefield of education, hermeneutics has played arelatively marginal role in research. It isthe task of this essay to introduce thegeneral methods and findings of Paul Ricoeur'shermeneutics. Specifically, the essayinterprets the usefulness of Ricoeur'sphilosophy in the study of domination. Theproblem of domination has been a target ofanalysis for critical pedagogy since itsinception. However, the role of interpretationas a constitutive part of ideology critique isrelatively understudied and it is here thatRicoeur's ideas are instructive. Last, theessay radicalizes Ricoeur's insights in orderto realize their potential to disruptasymmetrical relations of power in education. To this extent, the author contributes to thebuilding of a critical brand of hermeneutics,or the interpretation of domination.     

The Minho Word Pool: Norms for imageability,concreteness, and subjective frequency for 3,800 Portuguese words

Words are widely used as stimuli in cognitive research. Because of their complexity, using words requires strict control of their objective (lexical and sublexical) and subjective properties. In this work, we present the Minho Word Pool (MWP), a dataset that provides normative values of imageability, concreteness, and subjective frequency for 3,800 (European) Portuguese words—three subjective measures that, in spite of being used extensively in research, have been scarce for Portuguese. Data were collected with 2,357 college students who were native speakers of European Portuguese. The participants rated 100 words drawn randomly from the full set for each of the three subjective indices, using a Web survey procedure (via a URL link). Analyses comparing the MWP ratings with those obtained for the same words from other national and international databases showed that the MWP norms are reliable and valid, thus providing researchers with a useful tool to support research in all neuroscientific areas using verbal stimuli. The MWP norms can be downloaded along with this article or from http://p-pal.di.uminho.pt/about/databases.     

Infant sign training and functional analysis

We taught manual signs to typically developing infants using a reversal design and caregiver-nominated stimuli. We delivered the stimuli on a time-based schedule during baseline. During the intervention, we used progressive prompting and reinforcement, described by Thompson et al. (2004, 2007), to establish mands. Following sign training, we conducted functional analyses and verified that the signs functioned as mands. These results provide preliminary validation for the verbal behavior functional analysis methodology and further evidence of the functional independence of verbal operants.     

Short-term memory for temporal intervals: Contrasting explanations of the choose-short effect in pigeons

To better understand short-term memory for temporal intervals, we re-examined the choose-short effect. In Experiment 1, to contrast the predictions of two models of this effect, the subjective shortening and the coding models, pigeons were exposed to a delayed matching-to-sample task with three sample durations (2, 6 and 18 s) and retention intervals ranging from 0 to 20 s. Consistent with the coding model, the results suggested a sudden forgetting of memories for duration. In Experiment 2, to test the confusion hypothesis, the characteristics of the ITI and the retention interval differed. Contrary to the confusion hypothesis, a choose-short effect was obtained. In both experiments, a test with only two of the three comparison keys was performed. The results suggest three effects that may be controlling the birds’ responses: stimulus generalization when no retention interval is present; an increase in random responding at longer retention intervals; and, similarly, an increase in preference for the “short-sample” key at longer retention intervals.     

Endogenous modulation of compatibility effects: an Investigation into the temporal dynamics

Compatibility effects (CEs) arise when multiple stimuli fall within the visual field, providing an indication of stimulus processing. Previous research demonstrated that exogenous factors (e.g., luminance) influence the magnitude of CEs and their time course. The current research investigated the influence of endogenous factors. We used a flanker paradigm with a variable temporal delay (SOA) between a flanker and a subsequent central stimulus appearing. To manipulate endogenous factors, we required responses to the flanker on either half or all of the trials. The results indicate that increasing the task relevance of the flanker strengthened the initial positive CE (measured at short SOAs), consistent with past findings related to exogenous factors. However, at longer SOAs, the CE did not reverse into a negative CE, which stands against findings related to exogenous factors. These results indicate that CEs are subject to endogenous modulation, but the temporal dynamics do not mimic exogenous modulation.     

Evaluation of the accuracy,reliability, efficiency,and acceptability of fast forwarding to score problem behavior

Technological advances have allowed professionals to obtain extended recordings of caregiver–client interactions in natural settings, but scoring recorded video at normal speed to identify instances of low‐rate problem behavior is impractical in terms of scoring time. Fast forwarding is a continuous measurement system in which all seconds of an observation are viewed at a speed faster than normal. In Study 1, we evaluated whether three groups of five observers could discriminate problem behavior at three fast‐forwarding speeds across 10‐min observations. We analyzed the efficiency of using fast forwarding compared to continuous scoring, and interobserver agreement across the fast‐forwarding speeds. In Study 2, we compared the accuracy, efficiency, and social acceptability of fast forwarding (3.5x) and momentary time sampling (3.5 s) across 90‐min observations. Results support the use of 3.5x fast forwarding as a viable measurement system of improving the practicality of scoring problem behavior from video.     

Strategic control over saccadic eye movements: studies of the fixation offset effect

We studied the strategic (presumably cortical) control of ocular fixation in experiments that measured the fixation offset effect (FOE) while manipulating readiness to make reflexive or voluntary eye movements. The visual grasp reflex, which generates reflexive saccades to peripheral visual signals, reflects an opponent process in the superior colliculus (SC) between fixation cells at the rostral pole, whose activity helps maintain ocular position and increases when a stimulus is present at fixation, and movement cells, which generate saccades and are inhibited by rostral fixation neurons. Voluntary eye movements are controlled by movement and fixation cells in the frontal eye field (FEF). The FOE--a decrease in saccade latency when the fixation stimulus is extinguished--has been shown to reflect activity in the collicular eye movement circuitry and also to have an activity correlate in the FEF. Our manipulation of preparatory set to make reflexive or voluntary eye movements showed that when reflexive saccades were frequent and voluntary saccades were infrequent, the FOE was attenuated only for reflexive saccades. When voluntary saccades were frequent and reflexive saccades were infrequent, the FOE was attenuated only for voluntary saccades. We conclude that cortical processes related to task strategy are able to decrease fixation neuron activity even in the presence of a fixation stimulus, resulting in a smaller FOE. The dissociation in the effects of a fixation stimulus on reflexive and voluntary saccade latencies under the same strategic set suggests that the FOEs for these two types of eye movements may reflect a change in cellular activity in different neural structures, perhaps in the SC for reflexive saccades and in the FEF for voluntary saccades.     

Shifts in the psychometric function and their implications for models of timing

This study examined how two models of timing, scalar expectancy theory (SET) and learning to time (LeT), conceptualize the learning process in temporal tasks, and then reports two experiments to test these conceptualizations. Pigeons responded on a two-alternative free-operant psychophysical procedure in which responses on the left key were reinforceable during the first two, but not the last two, quarters of a 60-s trial, and responses on the right key were reinforceable during the last two, but not the first two, quarters of the trial. In Experiment 1 three groups of birds experienced a difference in reinforcement rates between the two keys only at the end segments of the trial (i.e., between the first and fourth quarters), only around the middle segments of the trial (i.e., between the second and third quarters), or in both end and middle segments. In Condition 1 the difference in reinforcement rate favored the left key; in Condition 2 it favored the right key. When the reinforcement rates differed in the end segments of the trial, the psychometric function--the proportion of right responses across the trial--did not shift across conditions; when it occurred around the middle of the trial or in both end and middle segments, the psychometric function shifted across conditions. Experiment 2 showed that the psychometric function shifts even when the overall reinforcement rate for the two keys is equal, provided the rates differ around the middle of the trial. This pattern of shifts of the psychometric function is inconsistent with SET. In contrast, LeT provided a good quantitative fit to the data.