Age of acquisition effects on an object‐name verification task

Naming latencies for words, objects and faces have been shown to be affected by the age at which an item is acquired (AoA). Originally, this effect was explained in terms of differential access to name representations. However, a number of recent studies have found AoA effects in tasks which do not require access to names (e.g. Brysbaert, Van Wijnendaele, & De Deynes, 2000 ; Lewis, 1999 ; Moore, Smith Spark, & Valentine, 2004 ; Moore & Valentine, 1999 ). Ellis and Lambon Ralph (2000) propose an alternative account of AoA, predicting that the effect should arise in any task where previously stored information is retrieved. The current study explored the effect of AoA on an object‐name verification task. Experiments 1 and 2 demonstrated that early acquired objects were verified significantly faster than later acquired objects. A third experiment collected naming latencies for the same picture stimuli in order to allow a comparison of the magnitude of the AoA effect for object verification and naming. The implications of these findings for accounts of AoA and its locus of effect are discussed.     

Substance P facilitation of memory: effects in an appetitively motivated learning task

Food deprived, heterogeneous strain (HS/IBG) mice were trained on two different discrimination tasks for food reinforcement. In one experiment animals were trained to make spatial discriminations in a T maze. Immediately after training they were given subcutaneous injections of either substance P (1 ng/g) or vehicle. Twenty-four hours later the animals were given reversal training in the same maze. The results showed that substance P-treated animals took significantly longer to acquire the reversal habit than did control mice. In a second experiment, animals were trained to make visual discriminations in a T maze. Immediately after reaching acquisition criterion animals were injected with either substance P (1 ng/g) or vehicle. Different groups of mice were retrained on the same task either 1, 2, 3, or 7 days after original learning. Savings scores were calculated and, at every interval, substance P-treated mice retained the task better than control animals. One interpretation of these data is that substance P-treated mice remembered the original task significantly better than vehicle-injected control animals.     

Semantic processing in an incidental learning task

Recent research on implicit learning has suggested that perceptual learning could account for the observed dissociation between task performance and associated verbal knowledge. We report three experiments that investigate whether performance in an incidental learning task is based on knowledge held primarily at a perceptual or a semantic level. The results indicate that, under the task conditions described, processing of the semantic content of the stimuli is an automatic process. The implications of this result for implicit learning are discussed.     

Physiological activity in an attribute learning task.

The relationship between the amount of information processing in an Attribute Learning task and autonomic activity, measured by skin conductance response (SCR), was investigated. The amount of information processing was manipulated by type of concept and feedback. Furthermore, the influence of practice and verbalization was studied.Three types of concepts were used: conjunction, exclusion and joint denial. The stimulus population consisted of four three-valued dimensions. The results showed that (1) SCR did not differ among concepts; (2) SCR varied with type of feedback, it being smallest at blanks and largest at infirming feedback; (3) SCR was related to the number of confirmations preceding infirmation; (4) subjects mainly used the strategy ‘reject hypothesis only after infirmation’; (5) subjects usually selected not-yet-tested hypotheses; (6) practice influenced performance; (7) verbalization did not result in more efficient use of information; however, the appropriateness of the experimental set-up to study this factor was questioned; (8) conjunction was easier to learn than the other concepts. The results were discussed in terms of uncertainty reduction, resulting from testing hypotheses in a concept learning task.     

Adding the goal to learn strengthens learning in an unintentional learning task

Previous research has demonstrated that contingency learning can take place in the absence of the intention to learn. For instance, in the color-word contingency learning task, each distracting word is presented most often in a given target color (e.g., "month" in red and "plate" in green), and less often in the other colors. Participants respond more quickly and accurately when the word is presented in the expected rather than an unexpected color, even though there is no reason why they would have the intention to learn the contingencies between the words and the colors. It remains to be determined, however, whether learning in such situations would benefit or suffer from adding the goal to learn contingencies. In the reported experiment, half of the participants were informed that each word was presented most often in a certain color, and they were instructed to try to learn these contingencies. The other half of the participants were not informed that contingencies would be present. The participants given the learning goal produced a larger response time contingency effect than did the control participants. In contrast to some results from other learning paradigms, these results suggest that intentional learning adds to, rather than interferes with, unintentional learning, and we propose an explanation for some of the conflicting results.     

Spacing effects in real‐world classroom vocabulary learning

As a primary goal, educators often strive to maximize the amount of information pupils remember. In the lab, psychologists have found efficient memory strategies for retaining school‐related materials. One such strategy is the spacing effect, a memory advantage that occurs when learning is distributed across time instead of crammed into a single study session. Spaced learning is not often explicitly utilized in actual classrooms, perhaps due to a paucity of research in applied settings and with school‐aged children. The current study examined the spacing effect in real‐world fifth‐grade classrooms. We taught 39 children unfamiliar English words using both massed and spaced learning. Five weeks later, we tested vocabulary recall. One‐week spacing produced superior long‐term retention compared to massed learning. This finding demonstrates that the spacing effect can be generalized to vocabulary learning in applied settings and middle‐school‐aged children. Copyright © 2010 John Wiley & Sons, Ltd.     

Shared learning shapes human performance: Transfer effects in task sharing

We investigated whether performing a task with a co-actor shapes the way a subsequent task is performed. In four experiments participants were administered a Simon task after practicing a spatial compatibility task with an incompatible S-R mapping. In Experiment 1 they performed both tasks alongside another person; in Experiment 2 they performed the spatial compatibility task alone, responding to only one stimulus position, and the Simon task with another person; in Experiment 3, they performed the spatial compatibility task with another person and the Simon task alone; finally, in Experiment 4, they performed the spatial compatibility task alone and the Simon task with another person. The incompatible practice eliminated the Simon effect in Experiments 1 and 4. These results indicate that when a task is distributed between two participants with each one performing a different part of it, they tend to represent the whole task rather than their own part of it. This experience can influence the way a subsequent task is performed, as long as this latter occurs in a social context.     

Order effects in contingency learning: The role of task complexity

Dennis and Ahn (2001) found that during contingency learning, initial evidence influences causal judgments more than does later evidence (a primacy effect), whereas López, Shanks, Almaraz, and Fernández (1998) found the opposite (a recency effect). We propose that in contingency learning, people use initial evidence to develop an anchoring hypothesis that tends to be underadjusted by later evidence, resulting in a primacy effect. Thus, factors interfering with initial hypothesis development, such as simultaneously learning too many contingencies, as in López et al., would reduce the primacy effect. Experiment 1 showed a primacy effect with learning contingencies involving only one outcome but no primacy effect with two outcomes. Experiment 2 demonstrated that the magnitude of the primacy effect correlated with participants' verbal working memory capacity. It is concluded that a critical moderator for exhibition of the primacy effect is task complexity, presumably because it interferes with initial hypothesis development.     

Temporal specificity of perceptual learning in an auditory discrimination task

Although temporal processing is used in a wide range of sensory and motor tasks, there is little evidence as to whether a single centralized clock or a distributed system underlies timing in the range of tens to hundreds of milliseconds. We investigated this question by studying whether learning on an auditory interval discrimination task generalizes across stimulus types, intervals, and frequencies. The degree to which improvements in timing carry over to different stimulus features constrains the neural mechanisms underlying timing. Human subjects trained on a 100- or 200-msec interval discrimination task showed an improvement in temporal resolution. This learning generalized to a perceptually distinct duration stimulus, as well as to the trained interval presented with tones at untrained spectral frequencies. The improvement in performance did not generalize to untrained intervals. To determine if spectral generalization was dependent on the importance of frequency information in the task, subjects were simultaneously trained on two different intervals identified by frequency. As a whole, our results indicate that the brain uses circuits that are dedicated to specific time spans, and that each circuit processes stimuli across nontemporal stimulus features. The patterns of generalization additionally indicate that temporal learning does not rely on changes in early, subcortical processing, because the nontemporal features are encoded by different channels at early stages.     

Instruction in learning a temporal pattern on an anticipation-coincidence task

Using a computer-simulated anticipation-coincidence task, the main aim of the study was to examine the effect of the type of instruction on learning a temporal pattern. For this task, participants must learn to anticipate the appropriate time to launch a projectile to hit a moving target. The experiment involved three instructional conditions. In the Explicit-rule Discover Instruction Condition participants were informed that target speed could change from trial to trial and that change is controlled by a regular pattern. Their task was then to search, to identify, and to use such pattern to enhance their anticipation. In the Explicit-Informative Instruction Condition, participants were, however, allowed before practice to examine attentively the regular pattern. Participants were also explicitly urged to use the pattern they observed to ensure a better interception of the target. Finally, in the Implicit Instruction Condition, participants were only informed that their task was to hit, or at least, to place the projectile as near as possible to the target. No additional information was provied about the target's behaviour. Analysis indicated that learning the temporal pattern was more important in Implicit than in Explicit-rule Discover Instruction Condion. However, the Explicit-Informative Instruction Condition produced unambiguouslly the highest learning. Overall, the study highlights the role of information over guidance in the understanding of the effect of the instructions on learning. Finally, we discussed the implications of these results on the comprehension of the variability of the effects of the instruction on learning.     

Context-outcome associations mediate context-switch effects in a human predictive learning task

Four experiments explored the role of contexts in information retrieval after different levels of acquisition training in human predictive learning. Participants were trained where cue (X) was followed by an outcome in context A while a different cue (Y) was followed by the absence of the outcome in context B. When 4 training trials with each cue were conducted, testing the stimuli in the alternative contexts decreased predictive judgments to X and increased predictive judgments to Y. These effects disappeared both when training was increased up to 18 trials (Experiments 1a and 1b), and when the outcome was presented in both contexts A and B (Experiments 2 and 4). When the outcome was presented in both contexts, the nonreinforced cue Y, trained in the presumably excitatory context B, became a conditioned inhibitor (Experiment 3). Additional experience with one of the contexts, but not with both, made the context-switch effect reappear (Experiment 4). These results suggest that irrelevant contexts may enter into direct associations with the outcome before prolonged training leads participants to discard them as predictors.     

Past midnight: Semantic processing in an implicit learning task

Four experiments are reported which examine the nature of representations underlying an implicit learning task. When shown a series of clock faces, each bearing a time between 6 and 12 o'clock, subjects subsequently show a selection preference for novel clock faces between these times. Furthermore, they show no signs of being aware of the underlying rule governing this preference. This effect is also present when the representation of time of day is changed from analogue to digital between learning and test. In the final experiment subjects show no preference for seen over unseen clocks between these critical times. These data suggest that, for this particular task, implicit learning involves abstract representations.     

The effects of cognitive feedback and task complexity in multiple-cue probability learning

Subjects learned three multiple-cue probability learning (MCPL) tasks of varying complexity under conditions of feedforward and cognitive feedback. Statistical information about the task was presented in the feedforward condition; in the cognitive feedback condition, subjects were given statistical information about their own performance in addition to information about the task. Task complexity was manipulated by varying the function forms relating the values of the cues to the values of the criterion: The least complex task contained three positive linear function forms, the intermediate task contained three inverted U-shaped function forms, and there was one negative linear function form, one inverted U-shaped function form, and one U-shaped function form in the most complex task. The hypothesis that cognitive feedback is more effective than feedforward for the more complex task used here was not confirmed: There were no differences between the two groups with regard to r_a (achievement), G (knowledge), or R_s,² (cognitive control). The level of performance on all tasks, including the complex nonlinear tasks, was very high under both conditions, however, an unexpected and important finding.     

A two‐part mixed effects model for cigarette purchase task data

The Cigarette Purchase Task is a behavioral economic assessment tool designed to measure the relative reinforcing efficacy of cigarette smoking across different prices. An exponential demand equation has become a standard model for analyzing purchase task data, but its utility is compromised by its inability to accommodate values of zero consumption. We propose a two‐part mixed effects model that keeps the same exponential demand equation for modeling nonzero consumption values, while providing a logistic regression for the binary outcome of zero versus nonzero consumption. Therefore, the proposed model can accommodate zero consumption values and retain the features of the exponential demand equation at the same time. As a byproduct, the logistic regression component of the proposed model provides a new demand index, the “derived breakpoint”, for the price above which a subject is more likely to be abstinent than to be smoking. We apply the proposed model to data collected at baseline from college students (N = 1,217) enrolled in a randomized clinical trial utilizing financial incentives to motivate tobacco cessation. Monte Carlo simulations showed that the proposed model provides better fits than an existing model. We note that the proposed methodology is applicable to other purchase task data, for example, drugs of abuse.     

Spatial S-R compatibility effects in an intentional imitation task

The active intermodal mapping hypothesis suggests that intentional imitation is mediated by a highly efficient, special-purpose mechanism of actor-centered movement encoding. In the present study, using methods from stimulus-response (S-R) compatibility research, we found no evidence to support this hypothesis. In two experiments, the performance of adult participants instructed to imitate actorcentered spatial properties of head, arm, and leg movements was affected by task-irrelevant, egocentric spatial cues. In Experiment 1, participants imitated using the same side of their bodies as did the model, and performance was less accurate when egocentric stimulus location was response incompatible than when it was response compatible. This effect was reversed in Experiment 2 when participants imitated using the opposite side of their bodies. These findings, in line with general process theories of imitation, imply that intentional imitation is mediated by the same processes that mediate responding to inanimate stimuli on the basis of arbitrary S-R mappings.     

Noradrenergic receptor blockade of the NTS attenuates the mnemonic effects of epinephrine in an appetitive light-dark discrimination learning task

These experiments examined the contribution of noradrenergic neurons in the nucleus of the solitary tract (NTS) in mediating the memory-facilitating effects of epinephrine. In Experiment 1, saline or 0.05 or 0.1 mg/kg of epinephrine was given intraperitoneally (ip) to rats after the second day of training in a light-dark Y-maze discrimination task. On a 20-trial retention test given 2 and 7 days later, the 0.1 mg/kg epinephrine group made significantly more correct responses than controls and required fewer trials to reach criterion. In Experiment 2, phosphate-buffered saline or the noradrenergic antagonist dl-propranolol (0.3 or 1.0 microg/0.5 microl) was infused into the NTS prior to an ip injection of saline or 0.1 mg/kg of epinephrine. The memory-enhancing effects of epinephrine were attenuated by the infusion of 0.3 microg/0.5 microl of dl-propranolol into the NTS. These findings indicate an involvement of NTS noradrenergic neurons in mediating the effects of peripheral epinephrine on memory storage processes.