A comparison of two techniques for reducing context-dependent forgetting

Recall is poorer when tested in a new environment than when tested in the original learning context. Two techniques for reducing this context-dependent forgetting were compared. One technique involved instructing subjects to recall their learning room(s), and the other attempted to establish multiple environmental retrieval cues by presenting lists in multiple rooms rather than all in the same room. Subjects were given three word lists to study in one or three rooms. All subjects were given a free-recall test in a new room, and half were asked to use remembered environmental context (EC) information to facilitate word memory. Multiple input contexts benefited only subjects who were uninstructed in the use of EC cues. Subjects given EC-recall instructions, however, recalled somewhat less in the three-room condition than in the one-room condition. The facilitative effects of the two techniques were not additive: EC-recall instructions benefited only one-room subjects. The results suggest that both EC-recall instructions and multiple learning contexts induce subjects to use contextual retrieval cues that are otherwise not spontaneously utilized, and that the greater the number of context cues stored in memory, the less accessible those cues become.     

Environmental context-dependent homophone spelling

Two experiments provided evidence of environmental context-dependent memory using a homophone spelling test (e.g., Jacoby & Witherspoon, 1982), an implicit, indirect measure of memory (Richardson-Klavehn & Bjork, 1988). Context reinstatement significantly increased priming in both experiments. The finding of environmental context reinstatement effects with this implicit memory test and others (Garberg & Radtke, 1986; Graf, 1988) indicates that the effect can be found reliably using a test that does not encourage subjects to generate their own context cues from memory.     

The role of memory consolidation in generalisation of new linguistic information

Accounts of memory that postulate complementary learning systems (CLS) have become increasingly influential in the field of language learning. These accounts predict that generalisation of newly learnt linguistic information to untrained contexts requires offline memory consolidation. Such generalisation should not be observed immediately after training, as these accounts claim unconsolidated representations are context and hippocampus-dependent and gain contextual and hippocampal independence only after consolidation. We trained participants on new affixes (e.g., -nule) attached to familiar word stems (e.g., buildnule), testing them immediately or 2days later. Participants showed an immediate advantage for trained affixes in a speeded shadowing task as long as these affixes occurred in the stem contexts in which they were learnt (e.g., buildnule). This learning effect generalised to words with untrained stems (e.g., sailnule) only in the delayed test condition. By contrast, a non-speeded definition selection task showed immediate generalisation. We propose that generalisation can be supported by initial context-dependent memories given sufficient processing time, but that context-independent lexical representations emerge only following consolidation, as predicted by CLS accounts.     

Temporal contexts: filling the gap between episodic memory and associative learning

People can create temporal contexts, or episodes, and stimuli that belong to the same context can later be used to retrieve the memory of other events that occurred at the same time. This can occur in the absence of direct contingency and contiguity between the events, which poses a challenge to associative theories of learning and memory. Because this is a learning and memory problem, we propose an integrated approach. Theories of temporal contexts developed in the memory tradition provide interesting predictions that we test using the methods of associative learning to assess their generality and applicability to different settings and dependent variables. In 4 experiments, the integration of these 2 areas allows us to show that (a) participants spontaneously create temporal contexts in the absence of explicit instructions; (b) cues can be used to retrieve an old temporal context and the information associated with other cues that were trained in that context; and (c) the memory of a retrieved temporal context can be updated with information from the current situation that does not fit well with the retrieved memory, thereby helping participants to best adapt their behavior to the future changes of the environment.     

Evidence for an implicit influence of memory on future thinking

The capacity to think about specific events that one might encounter in the future—episodic future thought— involves the flexible (re)organization of memory. The present study demonstrates that implicit processes play an important role here. In two experiments (N = 180), participants were asked to generate a personal event that they expected to plausibly occur in the following week. The content of the participants’ responses was biased (i.e., primed) by recent thoughts about a specific category of experiences. For instance, participants who had recently been induced to think about social experiences, in the context of an ostensibly unrelated task, were more likely than nonprimed participants to generate similar events occurring in their immediate future. Importantly, the participants were unaware of this unintentional influence of memory. The theoretical and practical implications of these findings for understanding episodic future thought and its relation to memory are discussed.     

Colour cues or spatial cues? Context-dependent preferences in the European greenfinch (<Emphasis Type="Italic">Carduelis chloris</Emphasis>)

Using featural cues such as colour to identify ephemeral food can increase foraging efficiency. Featural cues may change over time however; therefore, animals should use spatial cues to relocate food that occurs in a temporally stable position. We tested this hypothesis by measuring the cue preferences of captive greenfinches Carduelis chloris when relocating food hidden in a foraging tray. In these standardised associative learning trials, greenfinches favoured colour cues when returning to a foraging context that they had encountered before only once (“one-trial test”) but switched to spatial cues when they had encountered that scenario on ten previous occasions (“repeated-trial test”). We suggest that repeated encounters generated a context in which individuals had a prior expectation of temporal stability, and hence context-dependent cue selection. Next, we trained birds to find food in the absence of colour cues but tested them in the presence of visual distracters. Birds were able to learn spatial cues after one encounter, but only when visual distracters were identical in colouration. When a colourful distracter was present in the test phase, cue selection was random. Unlike the first one-trial test, birds were not biased towards this colourful visual distracter. Together, these results suggest that greenfinches are able to learn both cue types, colour cue biases represent learning, not simply distraction, and spatial cues are favoured over colour cues only in temporally stable contexts.     

Moveable Cues: a Practical Method for Reducing Context-Dependent Forgetting

In three experiments subjects studied a list of words under incidental learning conditions. Their explicit memory was tested using free recall. Relearning to criterion was also measured in Experiment 3. Testing took place at intervals after the study period of either 1 hour or 48 hours, and in the same or in a different environment. In all experiments either one or two ambient environmental context cues were present at study, which were then either present or not present at test. Ambient cues were found to reduce context-dependent forgetting, and practical uses of this method in applied settings are discussed. © 1997 by John Wiley & Sons, Ltd.     

When does a different environmental context make a difference in recognition? A global activation model

The effects on recognition of changes in environmental context between learning and test are examined. A context effect occurs when memory tests that take place in an environmental context that is different from the learning context produce consistent differences in performance. A formal model of context-dependent recognition within a global activation framework is presented. The model generates the predictions that (1) context effects will be present when items are tested in a new context that was not seen during learning and (2) context effects will be absent or very small when items are tested in a context that was experienced during learning but that differs from the context in which the test item was learned. Both predictions were verified in an experiment that varied the nature of the different-context test within subjects. Implications for research concerned with context-dependent recognition are discussed.     

Video context-dependent recall

In two experiments, we used an effective new method for experimentally manipulating local and global contexts to examine context-dependent recall. The method included video-recorded scenes of real environments, with target words superimposed over the scenes. In Experiment 1, we used a within-subjects manipulation of video contexts and compared the effects of reinstatement of a global context (15 words per context) with effects of less overloaded context cues (1 and 3 words per context) on recall. The size of the reinstatement effects in Experiment 1 show how potently video contexts can cue recall. A strong effect of cue overload was also found; reinstatement effects were smaller, but still quite robust, in the 15 words per context condition. The powerful reinstatement effect was replicated for local contexts in Experiment 2, which included a nocontexts-reinstated group, a control condition used to determine whether reinstatement of half of the cues caused biased output interference for uncued targets. The video context method is a potent way to investigate context-dependent memory.     

Developmental differences in children's context-dependent word learning

In this study, 2.5-, 3-, and 4-year-olds (N = 108) participated in a novel noun generalization task in which background context was manipulated. During the learning phase of each trial, children were presented with exemplars in one or multiple background contexts. At the test, children were asked to generalize to a novel exemplar in either the same or a different context. The 2.5-year-olds’ performance was supported by matching contexts; otherwise, children in this age group demonstrated context dependent generalization. The 3-year-olds’ performance was also supported by matching contexts; however, children in this age group were aided by training in multiple contexts as well. Finally, the 4-year-olds demonstrated high performance in all conditions. The results are discussed in terms of the relationship between word learning and memory processes; both general memory development and memory developments specific to word learning (e.g., retention of linguistic labels) are likely to support word learning and generalization.     

Referential Form and Memory for the Discourse History

The way we refer to things in the world is shaped by the immediate physical context as well as the discourse history. But what part of the discourse history is relevant to language use in the present? In four experiments, we combine the study of task-based conversation with measures of recognition memory to examine the role of physical contextual cues that shape what speakers perceive to be a part of the relevant discourse history. Our studies leverage the differentiation effect, a phenomenon in which speakers are more likely to use a modified expression to refer to an object (e.g., dotted sock) if they had previously described a similar object (e.g., striped sock) than when they had not described a similar object. Two physical cues—the background that framed the to-be-described pictures and the position of the pictures in the display—were manipulated to alter perceptions about the relevant discourse context. We measured the rate with which speakers modify referring expressions to differentiate current from past referents. Recognition memory measures following the conversation probed what was and was not remembered about past discourse referents and contexts. Analysis of modification rates indicated that these contextual grouping cues shaped perceptions about the relevant discourse context. The contextual cues did not affect memory for the referents, but the memory for past referents was better for speakers than for listeners. Our findings show that perceptions about the relevant discourse history are a key determinant of how language is used in the moment but also that conversational partners form asymmetric representations of the discourse history.     

Language context guides memory content

The relationship between language and memory was examined by testing accessibility of general knowledge across two languages in bilinguals. Mandarin-English speakers were asked questions such as “name a statue of someone standing with a raised arm while looking into the distance” and were more likely to name the Statue of Liberty when asked in English and the Statue of Mao when asked in Mandarin. Multivalent information (i.e., multiple possible answers to a question) and bivalent information (i.e., two possible answers to a question) were more susceptible to language dependency than univalent information (i.e., one possible answer to a question). Accuracy of retrieval showed language-dependent memory effects in both languages, while speed of retrieval showed language-dependent memory effects only in bilinguals’ more proficient language. These findings suggest that memory and language are tightly connected and that linguistic context at the time of learning may become integrated into memory content.     

Why I remember that: The influence of contextual factors on beliefs about everyday memory

In the present study, we examined the role of contextual factors in beliefs about remembering personal experiences. Specifically, we examined why individuals think that they remember experiences in everyday life and whether the reasons for remembering varied as a function of recall context, memory theme, and culture. In Experiment 1, we examined young adults’ reported memories in two hypothetical contexts. In Experiment 2, memories were reported in response to cue words in European American and Chinese young adults. The results indicated that social sharing contexts appeared to favor social functions, whereas private reminiscence contexts tended to favor nonfunctional reasons for remembering and, to a lesser extent, directive functions. The European Americans reported more functional reasons for remembering, whereas the Chinese were more likely to report external cues as a reason for remembering. Finally, self functions were rarely reported. The results are interpreted in light of theories of memory functions and the role of contextual factors on remembering.     

Flexible cue use in food-caching birds

An animal’s memory may be limited in capacity, which may result in competition among available memory cues. If such competition exists, natural selection may favor prioritization of different memory cues based on cue reliability and on associated differences in the environment and life history. Food-caching birds store numerous food items and appear to rely on memory to retrieve caches. Previous studies suggested that caching species should always prioritize spatial cues over non-spatial cues when both are available, because non-spatial cues may be unreliable in a changing environment; however, it remains unclear whether non-spatial cues should always be ignored when spatial cues are available. We tested whether mountain chickadees (Poecile gambeli), a food-caching species, prioritize memory for spatial cues over color cues when relocating previously found food in an associative learning task. In training trials, birds were exposed to food in a feeder where both spatial location and color were associated. During subsequent unrewarded test trials, color was dissociated from spatial location. Chickadees showed a significant pattern of inspecting feeders associated with correct color first, prior to visiting correct spatial locations. Our findings argue against the hypothesis that the memory of spatial cues should always take priority over any non-spatial cues, including color cues, in food-caching species, because in our experiment mountain chickadees chose color over spatial cues. Our results thus suggest that caching species may be more flexible in cue use than previously thought, possibly dependent upon the environment and complexity of available cues.     

To think or not to think,that is the question: Individual differences in suppression and rebound effects in autobiographical memory

Two studies explored the effects of forget instructions on autobiographical memory at immediate test and following delays of either 12–13 months, or 3–4 months. Using the Autobiographical Think/No-Think procedure (cf., Noreen & MacLeod, 2013), 24 never-depressed participants (Study 1) first generated 12 positive and 12 negative autobiographical memories and associated cues. Participants were then asked to recall the memory associated with some of the cues (i.e., ‘think’ condition), or to avoid saying or thinking about the memory associated with other cues (i.e., ‘no-think’ condition). Participants were then asked to recall the memories associated with all the cues at immediate test and following a delay of 12–13 months. Participants were found to be successful at forgetting both positive and negative autobiographical memories following ‘no-think’ instructions at immediate test but this forgetting effect did not persist following a 12–13 month delay. This pattern of remembering and forgetting was replicated in a second study (using 27 never-depressed participants) following a 3–4 month delay. Participants who had been less successful at forgetting ‘no-think’ memories at immediate test, were more likely to show rebound effects for those memories following a delay compared to memories which received neither ‘think’ nor ‘no-think’ instructions. Individual differences in inhibitory control and the efficacy of potential therapeutic interventions of ‘no-think’ instructions are considered.     

Gorillas’ use of the escape response in object choice memory tests

The ability to monitor and control one’s own cognitive states, metacognition, is crucial for effective learning and problem solving. Although the literature on animal metacognition has grown considerably during last 15 years, there have been few studies examining whether great apes share such introspective abilities with humans. Here, we tested whether four gorillas could meet two criteria of animal metacognition, the increase in escape responses as a function of task difficulty and the chosen-forced performance advantage. During testing, the subjects participated in a series of object choice memory tests in which a preferable reward (two grapes) was placed under one of two or three blue cups. The apes were required to correctly select the baited blue cup in this primary test. Importantly, the subjects also had an escape response (a yellow cup), where they could obtain a secure but smaller reward (one grape) without taking the memory test. Although the gorillas received a relatively small number of trials and thus experienced little training, three gorillas significantly declined the memory tests more often in difficult trials (e.g., when the location of the preferred reward conflicted with side bias) than in easy trials (e.g., when there was no such conflict). Moreover, even when objective cues were eliminated that corresponded to task difficulty, one of the successful gorillas showed evidence suggestive of improved memory performance with the help of escape response by selectively avoiding trials in which he would be likely to err before the memory test actually proceeded. Together, these findings demonstrate that at least some gorillas may be able to make optimal choices on the basis of their own memory trace strength about the location of the preferred reward.     

Context-dependence of implicit and explicit memory characteristics

The present experiments explore whether repetition priming in a word-stem completion task is context-dependent. In the first experiment, the environmental context was changed or remained constant at the testing stage. Implicit memory performance did not reveal any effects of environmental context. When tested by free recall, however, the same subjects showed an environmental congruency effect. On the other hand, effects of a change in presentation modality were restricted to implicit memory measures. In the second experiment, self-awareness was manipulated to create congruent or incongruent internal contexts at the testing stage. Performance on the word-stem completion task was seen to be influenced by internal contextual information. This pattern of results corroborates a processing account of implicit memory phenomena. Implicit and explicit expressions of memory utilize episodic information, but in a different way.     

The role of top-down knowledge about environmental context in egocentric distance judgments

Judgments of egocentric distances in well-lit natural environments can differ substantially in indoor versus outdoor contexts. Visual cues (e.g., linear perspective, texture gradients) no doubt play a strong role in context-dependent judgments when cues are abundant. Here we investigated a possible top-down influence on distance judgments that might play a unique role under conditions of perceptual uncertainty: assumptions or knowledge that one is indoors or outdoors. We presented targets in a large outdoor field and in an indoor classroom. To control visual distance and depth cues between the environments, we restricted the field of view by using a 14-deg aperture. Evidence of context effects depended on the response mode: Blindfolded-walking responses were systematically shorter indoors than outdoors, whereas verbal and size gesture judgments showed no context effects. These results suggest that top-down knowledge about the environmental context does not strongly influence visually perceived egocentric distance. However, this knowledge can operate as an output-level bias, such that blindfolded-walking responses are shorter when observers’ top-down knowledge indicates that they are indoors and when the size of the room is uncertain.

     

Learning, memorizing and apparent forgetting of chemical cues from new predators by Iberian green frog tadpoles

Many antipredator adaptations are induced by the prey’s ability to recognize chemical cues from predators. However, predator recognition often requires learning by prey individuals. Iberian green frog tadpoles (Pelophylax perezi) have the ability to learn new potential predators. Here, we tested the memory capabilities of Iberian green frog tadpoles. We conditioned tadpoles with chemicals cues from a non-predatory fish in conjunction with conspecific alarm cues, and examined whether tadpoles retained their conditioned response (reduction of activity level). We found that conditioned tadpoles reduced their activity levels in subsequent exposures to the non-predatory fish cues alone. Tadpoles were able to remember this association and reduced movement rate at least for 9 days after. The ability to learn and memorize potential predators may be especially important for the survivorship of prey species that are likely to find a high variety of predators. However, after those 9 days, there was a lack of response to the non-predatory fish cues alone in the absence of reinforcement. This could be explained if tadpoles behave according to the threat-sensitive predator avoidance hypothesis, and the perceived risk to the learning cue diminished over time, or it could be due to an apparent forgetting process to avoid non-adaptative responses to chemical cues of non-dangerous species that were randomly paired with alarm cues. Thus, this study demonstrates that green frog tadpoles in the absence of reinforcement remember the chemical cues of a learned predator only for a limited time that may be adaptative in a threat-sensitive context.     

The resistance of renewal to instructions that devalue the role of contextual cues in a conditioned suppression task with humans

The renewal of extinguished conditioned behaviour appears to reflect context-dependent learning. The present research used a conditioned suppression task with humans to examine whether instructions concerning the context could influence renewal. Pairings of a conditional stimulus (CS) and unconditional stimulus (US) were made in one context, followed by extinction trials of CS alone in a second context, and test trials of CS alone upon return to the original learning context. Four experiments tested whether the renewal of conditioned suppression observed during test would be attenuated if participants were instructed that the context changes were irrelevant to the predictive relationship between the CS and US. Using a differential conditioning design, no attenuation was found when the instructions were given prior to conditioning (Experiment 1) or immediately prior to the test trials (Experiment 2). The latter result was replicated with a single-cue conditioning design and further controls for exposure to the extinction contexts (Experiment 3). The collection of on-line ratings about the relationship between the contextual changes and the predictive nature of the CS indicated that participants did attend to and believe the instructions (Experiment 4). The results point to the resistance of renewal to explicit instructions that attempt to devalue the role of the contextual cues.