Adding drift to the decomposition of simple isochronous tapping: an extension of the Wing-Kristofferson model

The Wing-Kristofferson model (A. M. Wing & A. B. Kristofferson, (1973a, 1973b) decomposes the variance of isochronous finger tapping into 2 components: a central clock component and a peripheral motor component. The method assumes that there is no drift in the intertap intervals. A new method is introduced that further decomposes the clock component drift and drift-free clock variance. The method was studied through simulation and empirical analyses. Clock variance was the most prominent, followed by drift, and then motor variance. Individual and group differences were larger for the motor and drift variances than for the drift-free clock variance, so that group differences observed in the past may have been partially due to the failure to fully remove drift. The authors argue that the methods presented and extensions thereon show great promise in extending a method in wide use since 1973.     

We saw it all along: visual hindsight bias in children and adults

Abstract— We traced the developmental origins and trajectory of the hindsight bias. Three-, 4-, and 5-year-old children and adults identified gradually clarifying images of degraded common objects on a computer. Half the time, observers did not know in advance what the object would become. The rest of the time, observers knew the object's identity in advance and estimated when a naive same-age peer would identify the clarifying object. In two experiments, children and adults demonstrated hindsight bias by using advance knowledge to overestimate their same-age peers' ability to identify the objects. The magnitude of this bias declined across age in one experiment, but remained relatively stable over age in the other experiment. These findings link developmental psychology and adult cognitive science.     

The time course of consolidation in visual working memory

How long does it take to form a durable representation in visual working memory? Several theorists have proposed that this consolidation process is very slow. Here, we measured the time course of consolidation. Observers performed a change-detection task for colored squares, and shortly after the presentation of the first array, pattern masks were presented at the locations of each of the colored squares to disrupt representations that had not yet been consolidated. Performance on the memory task was impaired when the delay between the colored squares and the masks was short, and this effect became larger when the number of colored squares was increased. The rate of consolidation was approximately 50 ms per item, which is considerably faster than previous proposals.     

Social influence in pigeons (Columba livia): the role of differential reinforcement

Socially-influenced learning was studied in observer pigeons that observed a demonstrator in an adjacent chamber performing a target response comprising standing on a box and pecking a key 10 times. In Experiment 1 there was no evidence for social learning in the absence of reinforcement of the observer's behavior. When the target response was already established in the observer's repertoire, but was not differentially reinforced in relation to the demonstrator's behavior, rates of extinction were not influenced by the demonstrator's behavior (Experiment 2). Reinforcement of the observer's target response in the presence of the modeled target response, and not in its absence, resulted in control of the observer's responding by the behavior of the demonstrator (Experiments 3 and 4). This control was extended in Experiment 5 to deferred responses that occurred following a delay since the demonstrator's target responses. The acquisition of social influence depended on differential reinforcement of the observer's target response, with the demonstrator's target behavior serving as the explicit discriminative stimulus.     

On the form of the forgetting function: the effects of arithmetic and logarithmic distributions of delays

Forgetting functions with 18 delay intervals were generated for delayed matching-to-sample performance in pigeons. Delay interval variation was achieved by arranging five different sets of five delays across daily sessions. In different conditions, the delays were distributed in arithmetic or logarithmic series. There was no convincing evidence for different effects on discriminability of the distributions of different delays. The mean data were better fitted by some mathematical functions than by others, but the best-fitting functions depended on the distribution of delays. In further conditions with a fixed set of five delays, discriminability was higher with a logarithmic distribution of delays than with an arithmetic distribution. This result is consistent with the treatment of the forgetting function in terms of generalization decrement.     

Proprioceptive perception of phase variability

Previous work has established that judgments of relative phase variability of 2 visually presented oscillators covary with mean relative phase. Ninety degrees is judged to be more variable than 0 degrees or 180 degrees, independently of the actual level of phase variability. Judged levels of variability also increase at 180 degrees. This pattern of judgments matches the pattern of movement coordination results. Here, participants judged the phase variability of their own finger movements, which they generated by actively tracking a manipulandum moving at 0 degrees, 90 degrees, or 180 degrees, and with 1 of 4 levels of Phase Variability. Judgments covaried as an inverted U-shaped function of mean relative phase. With an increase in frequency, 180 degrees was judged more variable whereas 0 degrees was not. Higher frequency also reduced discrimination of the levels of Phase Variability. This matching of the proprioceptive and visual results, and of both to movement results, supports the hypothesized role of online perception in the coupling of limb movements. Differences in the 2 cases are discussed as due primarily to the different sensitivities of the systems to the information.     

Assessing the importance of letter pairs in reading-parafoveal processing is not the only view: reply to Inhoff, Radach, Eiter, and Skelly (2003)

D. Briihl and A. W. Inhoff (1995; see record 1995-20036-001) found that exterior letter pairs showed no privileged status in reading when letter pairs were presented as parafoveal primes. However, T. R. Jordan, S. M. Thomas, G. R. Patching, and K. C. Scott-Brown (2003; see record 2003-07955-013) used a paradigm that (a) allowed letter pairs to exert influence at any point in the reading process, (b) overcame problems with the stimulus manipulations used by Briihl and Inhoff (1995), and (c) revealed a privileged status for exterior letter pairs in reading. A. W. Inhoff, R. Radach, B. M. Eiter, and M. Skelly (2003; see record 2003-07955-014) made a number of claims about the Jordan, Thomas, et al. study, most of which focus on parafoveal processing. This article addresses these claims and points out that although studies that use parafoveal previews provide an important contribution, other techniques and paradigms are required to reveal the full role of letter pairs in reading.     

Spatial learning in the 5-HT1B receptor knockout mouse: selective facilitation/impairment depending on the cognitive demand

Age-related memory decline is associated with a combined dysfunction of the cholinergic and serotonergic systems in the hippocampus and frontal cortex, in particular. The 5-HT1B receptor occupies strategic cellular and subcellular locations in these structures, where it plays a role in the modulation of ACh release. In an attempt to characterize the contribution of this receptor to memory functions, 5-HT1B receptor knockout (KO) mice were submitted to various behavioral paradigms carried out in the same experimental context (water maze), which were aimed at exposing mice to various levels of memory demand. 5-HT1BKO mice exhibited a facilitation in the acquisition of a hippocampal-dependent spatial reference memory task in the Morris water maze. This facilitation was selective of task difficulty, showing thus that the genetic inactivation of the 5-HT1B receptor is associated with facilitation when the complexity of the task is increased, and reveals a protective effect on age-related hippocampal-dependent memory decline. Young-adult and aged KO and wild-type (WT) mice were equally able to learn a delayed spatial matching-to-sample working memory task in a radial-arm water maze with short (0 or 5 min) delays. However, 5-HT1BKO mice, only, exhibited a selective memory impairment at intermediate and long (15, 30, and 60 min) delays. Treatment by scopolamine induced the same pattern of performance in wild type as did the mutation for short (5 min, no impairment) and long (60 min, impairment) delays. Taken together, these studies revealed a beneficial effect of the mutation on the acquisition of a spatial reference memory task, but a deleterious effect on a working memory task for long delays. This 5-HT1BKO mouse story highlights the problem of the potential existence of "global memory enhancers."