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.     

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.     

Metacognitive control and optimal learning

The notion of optimality is often invoked informally in the literature on metacognitive control. We provide a precise formulation of the optimization problem and show that optimal time allocation strategies depend critically on certain characteristics of the learning environment, such as the extent of time pressure, and the nature of the uptake function. When the learning curve is concave, optimality requires that items at lower levels of initial competence be allocated greater time. On the other hand, with logistic learning curves, optimal allocations vary with time availability in complex and surprising ways. Hence there are conditions under which optimal strategies will be relatively easy to uncover, and others in which suboptimal time allocation might be expected. The model can therefore be used to address the question of whether and when learners should be able to exercise good metacognitive control in practice.     

Is focusing on unknown items while studying a beneficial long-term strategy?

The amount students learn is influenced by the decisions they make while they study. Prior research shows that when people decide what to study (and what not to), they almost universally prioritise information they do not know over information they do know. We found that focusing on unknown items was beneficial when memory was tested immediately after studying, but not when memory was tested after a delay of one or two weeks. These findings support a model in which studying unknown items causes many items to rise above a recall threshold, which results in a short-term advantage, but also leaves the items vulnerable to forgetting. Studying known items, by contrast, moves items farther above threshold, such that they remain above threshold for longer. These findings have implications for students and teachers who want to maximise long-term learning.     

Enhanced perceived responsibility decreases metamemory but not memory accuracy in obsessive-compulsive disorder (OCD)

Mixed findings have been obtained in prior research with respect to the presence and severity of memory and metamemory deficits in obsessive-compulsive disorder (OCD). We tested the hypothesis that experimentally induced increments of subjective responsibility would lead to a disproportionately strong decline of memory confidence and enhanced response latencies in OCD while leaving memory accuracy unaffected. Twenty-eight OCD patients and 28 healthy controls were presented a computerized memory test framed with two different scenarios. In the neutral scenario, the participant was requested to imagine purchasing 15 items from a do-it-yourself store. In the recognition phase, the 15 needed items were presented along with 15 distractor items. The participant was asked to decide whether items were on his or her shopping list or not, graded by subjective confidence. In the responsibility scenario, the general experimental setup was analogous except that the participant now had to envision that he or she was a helper in a region recently struck by an earthquake, dispatched to provide 15 urgently needed goods from a nearby town. In line with prior work by our group, samples did not differ in either condition on memory accuracy in a subsequent recognition task. As hypothesized, OCD participants were less certain in their responses for the high responsibility condition than controls. Whereas patients and controls did not differ in their subjective estimates for memorized items, patients expressed stronger doubt that their earthquake mission was successful. The findings indicate that low memory confidence in OCD may only be elicited in situations where perceived responsibility is high and that patients may share higher performance standards ("good is not good enough") than controls when perceived responsibility is inflated.     

Infants' learning,memory, and generalization of learning for bimodal events

Study 1 investigated whether infants 3 and 7 months of age show differential learning of and memory for sight-sound pairs depending on whether or not temporal synchrony was present; memory was assessed after a 10-min and 1-week interval. Study 2 examined whether 7-month-olds show generalization of learning when they encounter novel bimodal events that are similar (changes in size, orientation, or color, and spectral sound properties) to the sight-sound pairs learned 1 week earlier based on temporal synchrony. For Study 1, infants received a familiarization phase followed by a paired-comparison preference procedure to assess for learning of the sight-sound pairs. One week later a memory test was given. Results confirmed that 7-month-olds had no difficulty learning auditory-visual pairings regardless of whether or not events were temporally synchronous, and they remembered these 10 min and 1 week later. In contrast, 3-month-olds showed poorer learning of sight-sound associations in the no-synchrony than synchrony conditions, and memory for sight-sound pairs 1 week later was shown only for the synchrony conditions. Results for Study 2 revealed generalization of learning of bimodal pairings under all stimulus conditions after a 1-week interval at 7 months of age. Implications of these findings for development of intersensory knowledge are discussed.     

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.     

Distinct episodic contexts enhance retrieval-based learning

Spaced retrieval practice results in better long-term retention than massed retrieval practice. The episodic context account of this effect suggests that updated representations of the more distinct temporal contexts associated with spaced retrievals facilitate later recall. We examined whether environmental context, in addition to temporal context, may also play a role in retrieval-based learning. Participants studied and then attempted to retrieve the English translations of Swahili words during four acquisition blocks of trials. They were then randomly assigned to practice retrieving items three more times in one of the following conditions: massed practice with the same environmental context scene; massed practice with different environmental context scenes; spaced practice with the same environmental context scene; or spaced practice with different environmental context scenes. After a one-week delay, measures of recall, forgetting, and the joint probabilities between study session recall and final recall performance all indicated enhanced retention for both the spaced and different environmental context conditions. Indeed, after retrieving items in the study session, forgetting them during final recall was 371% more likely in the same context than in the different context conditions. These findings redefine and refine previous accounts of the episodic context model of retrieval-based learning.     

Path information effects in visual and proprioceptive spatial learning

Objects in an environment are often encountered sequentially during spatial learning, forming a path along which object locations are experienced. The present study investigated the effect of spatial information conveyed through the path in visual and proprioceptive learning of a room-sized spatial layout, exploring whether different modalities differentially depend on the integrity of the path. Learning object locations along a coherent path was compared with learning them in a spatially random manner. Path integrity had little effect on visual learning, whereas learning with the coherent path produced better memory performance than random order learning for proprioceptive learning. These results suggest that path information has differential effects in visual and proprioceptive spatial learning, perhaps due to a difference in the way one establishes a reference frame for representing relative locations of objects.     

Up-regulation of exploratory tendencies does not enhance general learning abilities in juvenile or young-adult outbred mice

"General cognitive ability" describes a trait that transcends specific learning domains and impacts a wide range of cognitive skills. Individual animals (including humans) exhibit wide variations in their expression of this trait. We have previously determined that the propensity for exploration is highly correlated with the general cognitive abilities of individual outbred mice. Here, we asked if inducing an increase in exploratory behaviors would causally promote an increase in animals' general learning abilities. In three experiments, juvenile and young-adult male CD-1 outbred mice were exposed to 12 novel environments starting at post-natal days 39 (juvenile) and 61 (young adult), after which they underwent a series of cognitive and exploratory tests as adults (beginning at post-natal day 79). Exposure to novel environments promoted increases in exploration (across multiple measures) on two different tasks, including an elevated plus maze. However, a subsequent test of general learning abilities (aggregate performance across five distinct learning tasks) determined that exposure to novel environments as juveniles or young-adults had no effect on general learning abilities in adulthood. Therefore, while exposure to novel environments promotes long-lasting increases in mice's exploratory tendencies, these increases in exploration do not appear to causally impact general learning abilities.     

Increased pupil dilation during tip-of-the-tongue states

Tip-of-the-tongue states (TOTs) are feelings of impending word retrieval success during a current failure to retrieve a target word. Though much is known and understood about TOT states from decades of research, research on potential psychophysiological correlates of the TOT state is still in its infancy, and existing studies point toward the involvement of neural processes that are associated with enhanced attention, motivation, and information-seeking. In the present study, we demonstrate that, during instances of target retrieval failure, TOT states are associated with greater pupillary dilation (i.e., autonomic arousal) in 91% of our sample. This is the first study to demonstrate a pupillometric correlate of the TOT experience, and this finding provides an important step toward understanding emotional attributes associated with TOT states. Mean pupil dilation also increased such that instances of target identification failure that were unaccompanied by TOT states < instances in which TOTs occurred < instances of target identification success. It is possible that TOTs reflect an intermediary state between complete target retrieval failure and full target retrieval.     

Rhesus monkeys (<Emphasis Type="Italic">Macaca mulatta</Emphasis>) discriminate between knowing and not knowing and collect information as needed before acting

Humans use memory awareness to determine whether relevant knowledge is available before acting, as when we determine whether we know a phone number before dialing. Such metacognition, or thinking about thinking, can improve selection of appropriate behavior. We investigated whether rhesus monkeys (Macaca mulatta) are capable of a simple form of metacognitive access to the contents of short-term memory. Monkeys chose among four opaque tubes, one of which concealed food. The tube containing the reward varied randomly from trial to trial. On half the trials the monkeys observed the experimenter baiting the tube, whereas on the remaining trials their view of the baiting was blocked. On each trial, monkeys were allowed a single chance to select the tube containing the reward. During the choice period the monkeys had the opportunity to look down the length of each tube, to determine if it contained food. When they knew the location of the reward, most monkeys chose without looking. In contrast, when ignorant, monkeys often made the effort required to look, thereby learning the location of the reward before choosing. Looking improved accuracy on trials on which monkeys had not observed the baiting. The difference in looking behavior between trials on which the monkeys knew, and trials on which they were ignorant, suggests that rhesus monkeys discriminate between knowing and not knowing. This result extends similar observations made of children and apes to a species of Old World monkey, suggesting that the underlying cognitive capacities may be widely distributed among primates.     

Extinction in human learning and memory

In two experiments, participants were given extinction training in a human causal learning task. In both experiments, three critical experimental cues were paired with different outcomes in a first phase of training and were then extinguished in a second phase. Three control cues were given the same treatment in the first phase of training, but were not then presented in the second phase. Participants' ability to correctly identify the outcome with which each cue had been paired in the first phase was lower for extinguished than for control cues. Causal attributions to the extinguished cues were also lower than those to the control cues, a difference that correlated with outcome memory. These data are consistent with the idea that extinction in causal judgement is due, at least in part, to a failure to remember the cue–outcome relationship encoded in the first phase of training.     

Monitoring memory errors: The influence of the veracity of retrieved information on the accuracy of judgements of learning

The current study examined the degree to which predictions of memory performance made immediately or at a delay are sensitive to confidently held memory illusions. Participants studied unrelated pairs of words and made judgements of learning (JOLs) for each item, either immediately or after a delay. Half of the unrelated pairs (deceptive items; e.g., nurse–dollar) had a semantically related competitor (e.g., doctor) that was easily accessible when given a test cue (e.g., nurse–do_ _ _r) and half had no semantically related competitor (control items; e.g., subject–dollar). Following the study phase, participants were administered a cued recall test. Results from Experiment 1 showed that memory performance was less accurate for deceptive compared with control items. In addition, delaying judgement improved the relative accuracy of JOLs for control items but not for deceptive items. Subsequent experiments explored the degree to which the relative accuracy of delayed JOLs for deceptive items improved as a result of a warning to ensure that retrieved memories were accurate (Experiment 2) and corrective feedback regarding the veracity of information retrieved prior to making a JOL (Experiment 3). In all, these data suggest that delayed JOLs may be largely insensitive to memory errors unless participants are provided with feedback regarding memory accuracy.     

Emergence and retention of learning in early fetal development

Prior research has demonstrated that the late-term fetus is capable of learning and then remembering a passage of speech for several days, but there are no data to describe the earliest emergence of learning a passage of speech, and thus, how long that learning could be remembered before birth. This study investigated these questions. Pregnant women began reciting or speaking a passage out loud (either Rhyme A or Rhyme B) when their fetuses were 28 weeks gestational age (GA) and continued to do so until their fetuses reached 34 weeks of age, at which time the recitations stopped. Fetuses’ learning and memory of their rhyme were assessed at 28, 32, 33, 34, 36 and 38 weeks. The criterion for learning and memory was the occurrence of a stimulus-elicited heart rate deceleration following onset of a recording of the passage spoken by a female stranger. Detection of a sustained heart rate deceleration began to emerge by 34 weeks GA and was statistically evident at 38 weeks GA. Thus, fetuses begin to show evidence of learning by 34 weeks GA and, without any further exposure to it, are capable of remembering until just prior to birth. Further study using dose–response curves is needed in order to more fully understand how ongoing experience, in the context of ongoing development in the last trimester of pregnancy, affects learning and memory.     

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).