Overshadowing by fixed- and variable-duration stimuli

Two experiments investigated the effect of the temporal distribution form of a stimulus on its ability to produce an overshadowing effect. The overshadowing stimuli were either of the same duration on every trial, or of a variable duration drawn from an exponential distribution with the same mean duration as that of the fixed stimulus. Both experiments provided evidence that a variable-duration stimulus was less effective than a fixed-duration cue at overshadowing conditioning to a target conditioned stimulus (CS); moreover, this effect was independent of whether the overshadowed CS was fixed or variable. The findings presented here are consistent with the idea that the strength of the association between CS and unconditioned stimulus (US) is, in part, determined by the temporal distribution form of the CS. These results are discussed in terms of time-accumulation and trial-based theories of conditioning and timing.     

The influence of temporal regularities on the implicit learning of pitch structures

Implicit learning is the acquisition of complex information without the intention to learn. The aim of this study was to investigate the influence of temporal regularities on the implicit learning of an artificial pitch grammar. According to the dynamic attending theory (DAT) external regularities can entrain internal oscillators that guide attention over time, inducing temporal expectations that influence perception of future events. In the present study, the presentation of the artificial pitch grammar in the exposure phase was temporally either regular or irregular for one of two participant groups. Based on the DAT, it was hypothesized that the regular temporal presentation would favour implicit learning of tone structures in comparison to the irregular temporal presentation. Results demonstrated learning of the artificial grammar for the group with the regular exposure phase and partial learning for the group with the irregular exposure phase. These findings suggest that the regular presentation helps listeners to develop perceptual expectations about the temporal occurrence of future tones and thus facilitates the learning of the artificial pitch grammar.     

Why we need cognitive explanations of autism

In the 70 years since autism was described and named there have been huge changes in the conceptualization of this enigmatic condition. This review takes a personal perspective on the history of autism research. The origins of the first cognitive theories of autism, theory of mind and weak central coherence, are discussed and updated to inform future developments. Selected experimental findings are interpreted in the historical context of changes that have been brought about by advances in methodology. A three-level framework graphically illustrates a causal chain between brain, mind, and behaviour to facilitate the identification of phenotypes in neurodevelopmental disorders. Cognition is placed at the centre of the diagram to reveal that it can link together brain and behaviour, when there are complex multiple mappings between the different levels.     

The impact of training sequence and between-category similarity on unsupervised induction

Studies of supervised categorization often show better learning when examples are presented in random alternation rather than massed by category, but such interleaving impairs learning in unsupervised tasks. The exemplar comparison hypothesis explains this result by assuming that people in unsupervised tasks discover generalizations about categories by comparing individual examples, and that interleaving increases the difficulty of such within-category comparisons. The category invention hypothesis explains the interleaving effect by assuming that people are more likely to merge or aggregate potentially separable categories when they are interleaved, and this initial failure to recognize separate categories then acts as an effective barrier to further learning. The present experiments show that the interleaving effect depends on the similarity or alignability of the presented categories. This result provides evidence in favour of the category invention hypothesis, which expects that highly dissimilar (nonalignable) categories will resist aggregation and hence will not be affected by interleaving. The nonmonotonic pattern of learning, and the interaction between sequence and similarity, observed in the alignable conditions of Experiment 3 were also consistent with category invention, but not with exemplar comparison. Implications are discussed for real-world learning, especially the relationship between exposure and learning and between supervised and unsupervised learning.     

Weighing the past and the future in decision making

Prior irreversible investments of money, time, or effort referred to as sunk costs frequently lead to decisions to continue a chosen course of action despite that this is irrational. With the aim of demonstrating that such escalation of commitment is a special case of a more general phenomenon, two experiments were carried out employing undergraduates as participants. Experiment 1 showed for fictitious personal and business investment scenarios that both prior losses and gains (sunk outcomes) affected choices to continue or discontinue the investment. In Experiment 2 the effect of sunk outcomes was reduced although not eliminated by a monetary bonus that in one condition depended on the future outcomes of the second gamble in two-stage gambles, in another condition on the future returns in personal investment scenarios. In support of a more inclusive theory subsuming escalation of commitment, the decisions were affected by both past and future outcomes and both gains and losses.     

The role of perceptual salience during the segmentation of connected speech

Statistical learning allows listeners to track transitional probabilities among syllable sequences and use these probabilities for subsequent speech segmentation. Recent studies have shown that other sources of information, such as rhythmic cues, can modulate the dependencies extracted via statistical computation. In this study, we explored how syllables made salient by a pitch rise affect the segmentation of trisyllabic words from an artificial speech stream by native speakers of three different languages (Spanish, English, and French). Results showed that, whereas performance of French participants did not significantly vary across stress positions (likely due to language-specific rhythmic characteristics), the segmentation performance of Spanish and English listeners was unaltered when syllables in word-initial and word-final positions were salient, but it dropped to chance level when salience was on the medial syllable. We argue that pitch rise in word-medial syllables draws attentional resources away from word boundaries, thus decreasing segmentation effectiveness.     

Spreading the words: A spacing effect in vocabulary learning

The spacing effect refers to the frequently observed finding that distributing learning across time leads to better retention than massing it into one single study session. In the present study, we examined whether the spacing effect generalises to primary school vocabulary learning. To this aim, children from Grade 3 were taught the meaning of 15 new words using a massed procedure and 15 other new words using a spaced procedure. The 15 words in the massed condition were divided into three sets of five words, and each set was taught three times in one of three learning sessions. In the spaced condition, learning was distributed across the three sessions: All 15 words were practised once in each of the three learning sessions. At the retention tests after 1 week and after 5 weeks we observed that the meaning of spaced words was remembered better than the meaning of massed words.     

Phases of procedural learning and memory: characterisation with perceptual-motor sequence tasks

ABSTRACT

Procedural learning and memory has been conceptualised as consisting of cognitive and autonomous phases. Although the Serial Reaction Time Task (SRTT) is a popular task used to study procedural memory (PM), it has not been used to explore the different phases of PM. The present study employed a modified SRTT and investigated whether it can distinguish phases of PM. Our results revealed that performance at the beginning of typing a repeating sequence was marked by a steep learning curve, followed by gradual improvements and ending in high performance levels without further improvement. Steep performance increases characterise the effortful learning of the cognitive phase, gradual increases at higher performances characterise emerging automatisation of the associative phase, and sustained highest performance characterises autonomous procedures when PM has formed. Our study presents an easy-to-use measure, capable of distinguishing phases of PM, and which can be useful to assess PM during brain development.     

An investigation of students' knowledge of the delayed judgements of learning effect

Judgements of learning (JOL) of paired associates can be made immediately after learning or after a delay, while viewing the first word (cue) only or both words (cue–target) in a pair. Delayed cue-only judgements are more related to subsequent memory performance than delayed cue–target, immediate cue-only, or immediate cue–target judgements. In two experiments we tested students' knowledge of this delayed JOL effect and whether their knowledge increases as a function of task experience (Experiment 2). The majority of the participants did not choose the more effective judgement strategy and they did not systematically alter their behaviour as a function of task experience. Instead, a subset of the participants selected judgement strategies on the basis of a learning goal, that is, a strategy that let them restudy both words in a pair. In sum, most students appear to be unaware of the powerful influence of delayed cue-only JOLs on monitoring accuracy.     

Using mnemonic images and explicit sound contrasting to help Japanese children learn English alphabet sounds

Although mnemonics have been shown to be effective in remembering letter-sound associations, the use of foreign words as cues for English phonemes had not been investigated. Learning phonemes in Japan is challenging because the Japanese language is based on a different sound unit called mora (mostly consonant-vowel combinations). This study investigated the effectiveness of using mnemonic images utilizing Japanese words as cues for the phonemes, and explicit sound contrasting of phonemic sounds with morae they could be confused with, in facilitating children's acquisition of knowledge about alphabet letter-sound correspondence. The participants were 140 6th-grade Japanese students who were taught phoneme-consonant correspondence, with or without the use of mnemonics or explicit sound contrasting. Analysis of the students’ pre- and post-instruction assessments revealed significant interaction effects between types of instruction provided and instruction phase, indicating better performance in letter-sound association as a consequence of the inclusion of both mnemonics and explicit sound contrasting.