Sleep does not enhance motor sequence learning

Improvements in motor sequence performance have been observed after a delay involving sleep. This finding has been taken as evidence for an active sleep consolidation process that enhances subsequent performance. In a review of this literature, however, the authors observed 4 aspects of data analyses and experimental design that could lead to improved performance on the test in the absence of any sleep consolidation: (a) masking of learning effects in the averaged data, (b) masking of reactive inhibition effects in the averaged training data, (c) time-of-day and time-since-sleep confounds, and (d) a gradual buildup of fatigue over the course of massed (i.e., concentrated) training. In 2 experiments the authors show that when these factors are controlled for, or when their effects are substantially reduced, the sleep enhancement effect is eliminated. Whereas sleep may play a role in protection from forgetting of motor skills, it does not result in performance enhancement.     

Visual context does not promote concurrent sequence learning

Concurrent sequence learning (CSL) of two or more sequences refers to the concurrent maintenance, in memory, of the two or more sequence representations. Research using the serial reaction time task has established that CSL is possible when the different sequences involve different dimensions (e.g., visuospatial locations versus manual keypresses). Recently some studies have suggested that visual context can promote CSL if the different sequences are embedded in different visual contexts. The results of these studies have been difficult to interpret because of various limitations. Addressing the limitations, the current study suggests that visual context does not promote CSL and that CSL may not be possible when the different sequences involve the same elements (i.e., the same target locations, response keys and effectors).     

Automaticity in motor sequence learning does not impair response inhibition

We examined the relationship between automaticity and response inhibition in the serial reaction time (SRT) task to test the common assertion that automatic behavior is ballistic. Participants trained for 3 h on the SRT, using blocks of a second-order conditional sequence interleaved with random blocks. Automaticity was measured using a concurrent secondary letter-counting task. Response inhibition was measured using a stop-signal task. RTs decreased with training, with a greater decrease for sequenced versus random blocks. Training correlated with a decreased RT cost to performing the secondary task concurrently with the SRT, indicating the development of automaticity. Crucially, there was no change in the ability to inhibit responses at the end of training, even in individuals who showed no dual-task interference. These results demonstrate that the ability to inhibit a motor response does not decrease with automaticity, suggesting that some aspects of automatic behavior are not ballistic.     

Response-to-stimulus interval does not affect implicit motor sequence learning, but does affect performance

Nissen and Bullemer (1987) reported that implicit motor sequence learning was disrupted by the addition of a secondary task. They suggested that this effect was due to the attentional load that the secondary task adds. Recently it has been suggested that the attentional load is not critical, but rather that the secondary task affects timing, either by lengthening or by making inconsistent the response-tostimulus interval (RSI)-that is, the delay between when a subject makes a response and when the next stimulus appears. In six experiments we manipulated the RSI and found no support for these two hypotheses. An inconsistent RSI did not adversely affect implicit motor sequence learning. A long RSI did not affect learning, although under some conditions subjects did not express learning if the RSI was long. These results are interpreted as reflecting the effects of attention.     

Redundant sensory information does not enhance sequence learning in the serial reaction time task

In daily life we encounter multiple sources of sensory information at any given moment. Unknown is whether such sensory redundancy in some way affects implicit learning of a sequence of events. In the current paper we explored this issue in a serial reaction time task. Our results indicate that redundant sensory information does not enhance sequence learning when all sensory information is presented at the same location (responding to the position and/or color of the stimuli; Experiment 1), even when the distinct sensory sources provide more or less similar baseline response latencies (responding to the shape and/or color of the stimuli; Experiment 2). These findings support the claim that sequence learning does not (necessarily) benefit from sensory redundancy. Moreover, transfer was observed between various sets of stimuli, indicating that learning was predominantly response-based.     

Aging affects motor learning but not savings at transfer of learning

Two important components of skill learning are the learning process itself (motor acquisition) and the ability to transfer what has been learned to new task variants (motor transfer). Many studies have documented age-related declines in the ability to learn new manual motor skills. In this study, I tested whether the degree of savings at transfer of learning is similarly affected by advancing age. Young and older adults made aiming movements with a joystick to hit targets presented on a computer screen, with real-time feedback display of their movement. They adapted to three different rotations of the feedback display in a sequential fashion, with return to the normal feedback display between each. Adaptation performance was better when it was preceded by other adaptive experiences, regardless of age.     

Ebbinghaus's contribution to the measurement of retention: savings during relearning

The focus here is on Ebbinghaus's sole measure of retention: savings during relearning. The article is divided into four sections: (a) the historical perspective surrounding Ebbinghaus's use of savings and relearning (including a fundamental difference between Ebbinghaus's conception of memory and that of his contemporaries such as William James), (b) potential problems with savings as a measure of retention, (c) recent findings based on savings and relearning, and (d) applications of savings and relearning.     

The basolateral amygdala is necessary for learning but not relearning extinction of context conditioned fear

Extinction of conditioned fear involves new learning that inhibits but does not eliminate the original fear memory. This inhibitory learning is thought to require activation of NMDA receptors (NMDAr) within the basolateral amygdala (BLA). However, once extinction has been learned, the role played by the BLA during subsequent extinction procedures remains unknown. The present study examined the role of neuronal activity and NMDAr activation in rats receiving their first or second extinction of context fear. We found that BLA infusion of DL-APV, a competitive antagonist of NMDAr, depressed fear responses at both the first and second extinction. It impaired learning extinction but spared and even facilitated relearning extinction. BLA infusion of muscimol, a GABA(A) agonist, produced a similar outcome, suggesting that DL-APV not only blocked NMDAr-dependent plasticity but also disrupted neuronal activity. In contrast, infusion of ifenprodil, a more selective antagonist of NMDAr containing the NR2B subunit, did not depress fear responses but impaired short- and long-term inhibition of fear at both the first and second extinction. Therefore, we suggest that relearning extinction normally requires NMDAr containing the NR2B subunit in the BLA. However, simultaneous blockade of these receptors and neuronal activity in the BLA results in compensatory learning that is able to promote long-term re-extinction. These data are consistent with a current model that attributes fear extinction to interactions between several neural substrates, including the amygdala and the medial prefrontal cortex.     

Ignored visual context does not induce latent learning

Psychonomic Bulletin & Review - People usually become faster at finding a visual target after repeated exposure to the same search display. This effect, known as contextual cueing, is often...     

Mixing topics while studying does not enhance learning

According to a recent survey, it is common for students to study two topics at the same time using flashcards, and students who do so virtually always keep the topics separate instead of mixing flashcards together (Wissman, Rawson, & Pyc, 2012). We predicted that mixing might be a relatively easy way to increase learning efficiency because mixing increases the spacing between repetitions of a given item, and spacing enhances long-term learning. We compared two conditions: in the mixed condition, participants alternated on each trial between studying anatomy terms and Indonesian translations. In the unmixed condition they studied one topic and then the other. Items were interleaved within item-type in both conditions. Mixing did not have reliable effects when participants studied flashcards in a single day (Experiments 1 and 2) or on two different days (Experiments 3 and 4). Thus, the results seem to disconfirm two sets of beliefs: students’ universal belief that mixing flashcards is undesirable and cognitive psychologists’ belief that doing so should be encouraged.     

Context-dependent savings in procedural category learning

Environmental context can have a profound influence on the efficacy of intervention protocols designed to eliminate undesirable behaviors. This is clearly seen in drug rehabilitation clinics where patients often relapse soon after leaving the context of the treatment facility. A similar pattern is commonly observed in controlled laboratory studies of context-dependent savings in instrumental conditioning, where simply placing an animal back into the original conditioning chamber can renew an extinguished instrumental response. Surprisingly, context-dependent savings in human procedural learning has not been carefully examined in the laboratory. Here, we provide the first known empirical demonstration of context-dependent savings in a perceptual categorization task known to recruit procedural learning. We also present a computational account of these savings using a biologically detailed model in which a key role is played by cholinergic interneurons in the striatum.     

Implicit motor sequence learning is not purely perceptual

Many reports have indicated that implicit learning of sequences in a choice response time task is primarily perceptual; subjects learn the sequence of stimuli rather than the sequence of motor responses. Three experiments tested whether implicit motor sequence learning could be purely perceptual: no support was found for that hypothesis. Subjects who merely watched stimuli did not learn the sequence implicitly (Experiment 1), and sequence learning transferred robustly to a different set of stimulus cues (Experiment 2). In the final experiment, the stimulus-response mapping was changed at transfer so that one group of subjects pushed the same sequence of keys but saw new stimuli, whereas another group pushed a different sequence of keys but saw the same stimuli. Transfer to the new mapping was shown only if the motor sequence was kept constant, not the perceptual sequence. It is proposed that subjects learn a sequence of response locations in this and similar tasks.     

Recall is not necessary for verbal sequence learning

The question of whether overt recall of to-be-remembered material accelerates learning is important in a wide range of real-world learning settings. In the case of verbal sequence learning, previous research has proposed that recall either is necessary for verbal sequence learning (Cohen & Johansson Journal of Verbal Learning and Verbal Behavior, 6, 139–143, 1967; Cunningham, Healy, & Williams Journal of Experimental Psychology: Learning, Memory, and Cognition, 10, 575–597, 1984), or at least contributes significantly to it (Glass, Krejci, & Goldman Journal of Memory and Language, 28, 189–199, 1989; Oberauer & Meyer Memory, 17, 774–781, 2009). In contrast, here we show that the amount of previous spoken recall does not predict learning and is not necessary for it. We suggest that previous research may have underestimated participants’ learning by using suboptimal performance measures, or by using manual or written recall. However, we show that the amount of spoken recall predicted how much interference from other to-be-remembered sequences would be observed. In fact, spoken recall mediated most of the error learning observed in the task. Our data support the view that the learning of overlapping auditory–verbal sequences is driven by learning the phonological representations and not the articulatory motor responses. However, spoken recall seems to reinforce already learned representations, whether they are correct or incorrect, thus contributing to a participant identifying a specific stimulus as either “learned” or “new” during the presentation phase.     

Causal order does not affect cue selection in human associative learning

Waldmann and Holyoak (1992) presented evidence in support of the claim that cue selection does not emerge in “diagnostic” human learning tasks in which the cues are interpretable as effects and the outcomes as the causes of those effects. Waldmann and Holyoak argued that this evidence presents a major difficulty for associationist theories of learning and instead supports a “causal model” theory. We identify a number of flaws in Waldmann and Holyoak’s experimental procedures and report three new experiments designed to test their claim. In Experiment 1, cue selection was observed regardless of causal order and regardless of whether the cues were abstractly or concretely specified. In Experiments 2 and 3, cue selection was again observed when subjects predicted causes from effects. We conclude that our results are consistent with simple associationist theories of learning but contradict Waldmann and Holyoak’s causal model theory.     

Implicit motor sequence learning is not represented purely in response locations

This study employed a novel variant of the serial reaction time task, focused on sequencing one element of movement—direction. During the task a repeated pattern of alternating directions (right–left–right, etc.) was embedded in the stimuli, and there was no series of response locations. Responses were made via two effector systems: single-finger responding (necessitates lateral arm movements between response keys), and four-fingered responding (4 individual fingers on 4 individual keys; requires no lateral arm movement). The sequence of directions was only learned by participants who performed lateral movements during training, indicating that learning was contingent on the particular motor effector used. Participants with low levels of sequence awareness displayed the same pattern of results.     

Working memory load in the initial learning phase facilitates relearning: a study of vocabulary learning

In this study, the effect of working memory load in the initial learning phase on the relearning phase was examined. Exp. 1 examined the effect of articulatory suppression in paired associative learning with a relearning method. In the learning phase, 28 participants (M age=21.8 yr., SD=2.1) learned all word-nonword associations under conditions of articulatory suppression or simple tapping. After a delay, they answered a cued recall task in a nonsuppressed condition and a relearning task in a simple tapping condition. The subjects who learned under the simple tapping condition in the learning phase required significantly more trials in the relearning phase. In Exp. 2, 28 participants (M age=20.8 yr., SD=1.5) participated, and the result was replicated. These results suggested that working memory load facilitates relearning. Results are best explained by contextual interference (Battig) rather than by the less-is-more hypothesis of Newport.     

Threat captures attention but does not affect learning of contextual regularities

Some of the stimulus features that guide visual attention are abstract properties of objects such as potential threat to one's survival, whereas others are complex configurations such as visual contexts that are learned through past experiences. The present study investigated the two functions that guide visual attention, threat detection and learning of contextual regularities, in visual search. Search arrays contained images of threat and non-threat objects, and their locations were fixed on some trials but random on other trials. Although they were irrelevant to the visual search task, threat objects facilitated attention capture and impaired attention disengagement. Search time improved for fixed configurations more than for random configurations, reflecting learning of visual contexts. Nevertheless, threat detection had little influence on learning of the contextual regularities. The results suggest that factors guiding visual attention are different from factors that influence learning to guide visual attention.     

Cue location does not account for all selective associations in food aversion learning

Studies of food aversion learning have been widely interpreted as yielding evidence for selectivity in the associability of cues and consequences. On the one hand, taste cues were easily conditioned to interoceptive consequences (e.g. “illness”), but only with difficulty to exteroceptive consequences (e.g. shock). On the other hand, audiovisual stimuli were easily conditioned to shock, but only with difficulty to illness (Revusky and Garcia, 1970). Sullivan (1984) has emphasized that cue location and temporality have been important uncontrolled variables in many food-aversion studies and has argued that when these factors are taken into account, the supposed selectivity related to sensory modality is lost. Thus, Sullivan (1984) argues that shocks, like “illness”, are readily associated with tastes provided that the tastes are intrinsic attributes of the substances ingested.

Sullivan's important article may have demonstrated significant weaknesses in the evidence for specific associations of exteroceptive cues with shock rather than with “illness”, and this point will not be considered further. However, there are two aspects of Sullivan's case that cannot be substantiated. Firstly, the attempt to demonstrate that taste cues are as readily associated with shock as they are with “illness” is unconvincing. Secondly, unjustified assumptions are made about the nature of the unconditioned stimulus in conditioning with interoceptive consequences, which is presumed to be “illness” despite extensive evidence to the contrary.     

Recognition of conspecific odors by laboratory rats (Rattus norvegicus) does not show context specificity

This experiment investigated how contextual cues affect recognition of conspecific odors in laboratory rats (Rattus norvegicus). Rats received 5 encounters with the same odor in the same context. For the 6th test encounter, all rats received a simultaneous presentation of the original odor and a novel odor. The authors tested 1 group of rats (context same) in the same context as before. For the remaining 2 groups, the test encounter was in a different context that 1 group (context different) had experienced but that 1 group (context novel) had not. A significant preference to investigate the novel odor by context-same and context-different rats, but not by context-novel rats, suggests that odor recognition can occur following transfer to a different, but familiar, test context, indicating a lack of context specificity.     

Chronic, severe hypertension does not impair spatial learning and memory in Sprague-Dawley rats

This study tested the hypothesis that long-term hypertension impairs spatial learning and memory in rats. In 6-wk-old Sprague-Dawley rats, chronic hypertension was induced by placing one of three sizes of stainless steel clips around the descending aorta (above the renal artery), resulting in a 20–80-mm Hg increase of arterial pressure in all arteries above the clip, that is, the upper trunk and head. Ten months later, the rats were tested for 5 d in a repeated-acquisition water maze task, and on the fifth day, they were tested in a probe trial; that is, there was no escape platform present. At the end of the testing period, the nonsurgical and sham control groups had similar final escape latencies (16±4 sec and 23±9 sec, respectively) that were not significantly different from those of the three hypertensive groups. Rats with mild hypertension (140–160 mm Hg) had a final escape latency of 25±6 sec, whereas severely hypertensive rats (170–199 mm Hg) had a final escape latency of 21±7 sec and extremely hypertensive rats (>200 Hg) had a final escape latency of 19±5 sec. All five groups also displayed a similar preference for the correct quadrant in the probe trial. Together, these data suggest that sustained, severe hypertension for over 10 mo is not sufficient to impair spatial learning and memory deficits in otherwise normal rats.