Idiosyncratic route-based memories in desert ants, Melophorus bagoti: how do they interact with path-integration vectors?

Individually foraging desert ants of central Australia, Melophorus bagoti, exhibit amazingly precise mechanisms of visual landmark guidance when navigating through cluttered environments. If trained to shuttle back and forth between the nest and a feeder, they establish habitual outbound and inbound routes, which guide them idiosyncratically across the natural maze of extended arrays of grass tussocks covering their foraging areas. The route-based memories that usually differ between outbound and inbound runs are acquired already during the first runs to the nest and feeder. If the ants are displaced sideways of their habitual routes, they can enter their stereotyped routes at any place and then follow these routes with the same accuracy as if they had started at the usual point of departure. Furthermore, the accuracy of maintaining a route does not depend on whether homebound ants have been captured at the feeder shortly before starting their home run and, hence, with their home vector still fully available (full-vector ants), or whether they have been captured at the nest after they had already completed their home run (zero-vector ants). Hence, individual landmark memories can be retrieved independently of the state of the path-integration vector with which they have been associated during the acquisition phase of learning. However, the ants display their path-integration vector when displaced from the feeder to unfamiliar territory.     

Internal causes of return trip effect based on eye movement and EEG indices

When traveling by car, the driver normally feels that the return trip is shorter than the outbound trip. The reason for this feeling, called return trip effect, is not clear. To explore the internal causes of this return trip effect, an indoor driving simulation experiment and a real car driving experiment were performed in this study. Questionnaires were used to obtain the estimated time of the outbound and return trips of the drivers. An eye tracker and an electroencephalograph equipment were used to record driver's eye movement and EEG data in the real-car driving experiment. The physiological indices and questionnaire results showed that the difference in the driver's cognitive loads of the outbound and return trips was the internal cause of the return trip effect. Drivers who were unfamiliar with the road had a different cognitive load between the two trips, which resulted in the return trip effect. However, drivers who were familiar with the road did not experience a return trip effect due to the close cognitive loads of the two trips.     

Not using the obvious: desert ants, Melophorus bagoti, learn local vectors but not beacons in an arena

Many ant species travel large distances to find food, sometimes covering distances that are up to one million times their body length. Even when these foraging trips follow convoluted paths, the ants usually find their way back to their nest with precision (Wehner et al. in J Exp Biol 199:129–140, 1996). Ants have been shown to use both compass cues in the sky (pattern of polarised light) and landmarks on Earth to return to their nest. We present two experiments conducted on a solitary foraging ant: Melophorus bagoti in their natural habitat in the central Australian desert. Ants were trained and tested in situ. We tested foragers’ ability to exit a circular arena which provided an undifferentiated panorama. Artificial visual landmarks were located near a small exit. On tests in which path integration information was not available, foragers did not use artificial landmarks as beacons. Instead, they oriented in the learned exit direction, whether or not it pointed to the nest. We suggest that M. bagoti foragers learned a context-specific local vector when cued by the context of the circular arena. Our findings present the first evidence that M. bagoti foragers learn context-specific compass directions to chart their initial path home.     

Autobiographical memory specificity in adults reporting repressed,recovered, or continuous memories of childhood sexual abuse

Some psychotherapists believe that adult survivors of childhood sexual abuse (CSA) are characterised by memory deficits for their childhood. Using the Autobiographical Memory Test (AMT), we asked nonabused control participants and participants who reported either continuous, recovered, or repressed memories of CSA to retrieve a specific personal memory in response to either positive or negative cue words from either childhood or adolescence/adulthood. The results indicated that participants who believed they harboured repressed memories of abuse tended to exhibit the greatest difficulty retrieving specific memories from their childhood. Neither posttraumatic stress disorder (PTSD) nor major depression was related to diminished memory specificity.     

Reminders can enhance or impair episodic memory updating: a memory-for-change perspective

ABSTRACT

The Memory-for-Change framework proposes that retrieving episodic memories can facilitate new learning when changes between existing memories and new information are integrated during encoding and later recollected. Four experiments examined whether reminders could improve memory updating and enhance new learning. Participants studied two study lists of word pairs and were given a cued recall test on responses from both lists. Reminders of List 1 words pairs (A-B) appeared immediately before List 2 words pairs that included repeated cues and changed responses (A-D). Across experiments, we varied the types of reminders to determine whether differences in their effectiveness as retrieval cues would influence memory for the list membership of responses. We found that presenting intact reminders (cue-response) enhanced the memory benefits associated with recollection-based retrieval of changes relative to when no reminders appeared and when partial reminders (cue-only) appeared with and without feedback. Importantly, cue-response reminders benefitted memory when they were recognised in List 2 and when changes were later recollected. This suggests that integrative encoding can be facilitated when substantial environmental support is available to cue retrieval of existing memories. These findings have practical implications for understanding which reminders best aid the correction of memories for inaccurate information.     

Retrieval‐induced forgetting of emotional and unemotional autobiographical memories

This experiment extended the retrieval‐induced forgetting (RIF) procedure from simple, episodic information to emotional and unemotional autobiographical memories. In the elicitation phase, participants generated specific memories from their past in response to negative, neutral, or positive category cues. In the retrieval‐practice phase, they practised retrieving (and elaborated further on) some of the memories for some of the categories. In the final test phase, they tried to recall all memories. Memories that received retrieval practice were recalled more often on final test than baseline memories, whereas memories that were not practised, yet competed with practised memories via a shared category cue, were recalled less often than baseline memories. We discuss the roles of inhibition, competition, emotion, and self‐relevance, and consider what laboratory manipulations of memory might reveal about everyday and pathological personal memory.     

The effects of cue modality on the quality of personal memories retrieved

We investigated the effect of cue modality on the specificity, speed, vividness, and age of autobiographical memory retrieval. Cues were presented as either an odour, a visual image, or a word label. Odour-cued memories were older, more likely to be categoric, and were slower to be retrieved. Few gender differences were found although females reported more vivid memories than males. We suggest that cue modality directly affects retrieval processes; odour cues are more likely to initiate a perceptual search strategy, in contrast to memories cued by visual images and words, which are usually conceptually/verbally mediated.     

How intention to retrieve a memory and expectation that a memory will come to mind influence the retrieval of autobiographical memories

While involuntary memories are retrieved with no intention and are usually unexpected (when one is not waiting for a memory to arise), voluntary memories are intended and expected (when one is searching and waiting for a memory to arise). The present study aimed to investigate the effects of retrieval intentionality (i.e. wanting to retrieve a memory) and monitoring processes (i.e. waiting for a memory to appear) during autobiographical memory retrieval. In addition, we introduced two novel laboratory conditions that have not been used in previous research on voluntary memories: in the first, participants were asked to report anything they could think of in response to each cue word; in the second, they could skip a word if nothing came to mind. These novel manipulations allowed us to differentiate between voluntary memories retrieved in response to experimenter-generated cues (when participants were forced to provide a memory or a thought for each cue) and self-selected cues (when participants were free to not answer a cue if they found it too difficult). We found that highly accessible memories were mostly experienced when retrieval was involuntary and unexpected, while memories with low accessibility were accessed through intentional retrieval and monitoring processes. Response times for memories recalled in the experimenter-generated cue conditions were longer compared to the self-selected cue conditions. This novel finding shows that experimenter-generated recall favours memories with low accessibility; it further supports the idea that, in a substantial number of trials, voluntary memories are directly rather than effortfully retrieved. The idea that the driving force behind differences between involuntary and voluntary memories is not the intention per se is further discussed.     

The Effect of Religious Short‐Term Mission Trips on Youth Civic Engagement

Religious short‐term mission trips are an increasingly popular form of American religious practice, especially among young people. Both organizers and participants often emphasize their transformative nature. However, scholarly efforts to evaluate systematically the social consequences of religious short‐term mission trips are lacking. To address this neglect, our article investigates whether going on a religious short‐term mission trip significantly differentiates youth who engage in civic actions from those who do not. Based on quantitative analysis of Wave I of the National Survey of Youth Religion (NSYR), we find that, controlling for other important factors, taking a mission trip significantly increases the likelihood of adolescents participating in various forms of civic activity, particularly religious‐based volunteer work. Drawing on prior scholarship on religious short‐term mission and similarly focused trips and in‐depth interview data from trip participants, we outline several theoretical mechanisms that likely explain the link between taking a mission trip and civic engagement.     

Configural Processing in Memory Retrieval: Multiple Cues and Ensemble Representations

When retrieving information from memory, a number of contextual cues may interact to determine which ideas will be easily accessible. Even the simplest case in which joint cue action obtains (two cues) is very revealing of the principles of memory access and representation of compounds. Mechanisms by which dual cues interact to constrain retrieval from episodic memory are considered. A holistic mechanism of cue integration is contrasted with two nonholistic mechanisms: a multiplicative or intersection mechanism and an independent-contributions mechanism. Holistic- and intersection-cuing mechanisms are consistent with different variants of compound cue models of priming. The independent cuing mechanism is consistent with spreading activation models of priming. Data from four experiments which examined dual-cued recognition of items from (newly learned) triples demonstrated strongly configural, holistic, action of dual cues. The two cues and test item must form an encoded compound to yield cuing advantages. Two independent cues to the test item are ineffective if the two cues and test were not learned together as a triple; one valid and one invalid cue are also ineffective. This is so despite the availability of pairwise information for each cue–test relation, and despite the fact that these cues are effective when operating alone. A compound cue model which predicts precisely this surprising pattern of priming is developed. The compound cue model also predicts previously obtained configural priming of associative judgments, as well as the bias priming generally observed in item recognition and similar paradigms.     

Activating attachment representations impact how we retrieve autobiographical memories

Although much research indicates that proximity to attachment figures confers many psychological benefits, there is little evidence pertaining to how attachment activation may impact autobiographical memory retrieval. Following a negative mood induction to elicit overgeneral autobiographical retrieval, participants (N?=?70) were administered an induction in which they imagined a person who is a strong attachment figure or an acquaintance. Participants then completed an autobiographical memory task to retrieve memories in response to neutral and negative cue words. Attachment priming resulted in less distress, increased retrieval of specific memories, and reduced retrieval of categoric memories. These findings indicate that activation of mental representations of attachment figures can impact on the specificity of autobiographical memory retrieval, and extends prevailing models of autobiographical memory by integrating them with attachment theory.     

Reduced specificity of emotional autobiographical memories following self-regulation depletion

The present study used a Color Stroop task, involving naming the ink colors of incongruous color words, to deplete self-regulation resources prior to retrieving a series of autobiographical memories to emotional and neutral cue words--the Autobiographical Memory Test (AMT). Control participants either read color words written in black ink or performed no task prior to the AMT. Difficulty accessing specific memories on the AMT has been shown to index key aspects of the onset and maintenance of depression and other emotional disorders. Our hypothesis that depleted participants would retrieve fewer specific memories to cues on the AMT relative to controls was supported, even when levels of depressed and anxious mood, an index of clinical depression, posttraumatic stress, and verbal intelligence were covaried. The results indicate that self-regulation depletion via a neutral, unrelated task can impact on emotion-related autobiographical memory processes that have been shown to be dysfunctional in emotionally disordered populations.     

Trauma and autobiographical memory specificity in depressed inpatients

Research on autobiographical memory has shown that clinical depression is associated with a difficulty in retrieving specific autobiographical memories in response to cue words. This study examined the relation between lack of autobiographical memory specificity and self-reported trauma in a group of depressed adults (N = 23). In addition to the Autobiographical Memory Test (AMT; Williams & Broadbent, 1986) participants completed a number of questionnaires assessing the presence of traumatic experiences in the past, level of depression and neuroticism. The number of specific responses was not related to depression severity, but was significantly associated with the presence and severity of reported physical abuse. Participants who had been victim of physical abuse were less specific than participants who had not been confronted with such physical adversities. The results are discussed in the context of a functional hypothesis about the developmental relations between memory specificity, trauma and depression.     

The principle of good continuation in space and time can guide visual search in absence of priming or contextual cueing

Previous research has shown that repetition of the same target features and/or spatial location over time can improve detection, discrimination, and identification. It has also been shown that repetition of the same distractor features or spatial layout can similarly improve search performance. Thus, it appears that target and distractor features and positions are stored in memory and used to guide visual processes such as object recognition and search. Here we introduce a new paradigm for manipulating the sequential structure of target position across trials independently of target features, position priming, and contextual configuration. Results show that facilitation or inhibition in visual search occurs when the target appears at an implicitly expected or unexpected location, respectively, according to the Gestalt's principle of good continuation of the target's successive positions across trials. These findings provide evidence that the simple rule of good continuation can act as a spatiotemporal cue and guide where to attend while searching for the target.     

More than a feeling: Emotional cues impact the access and experience of autobiographical memories

Remembering is impacted by several factors of retrieval, including the emotional content of a memory cue. Here we tested how musical retrieval cues that differed on two dimensions of emotion—valence (positive and negative) and arousal (high and low)—impacted the following aspects of autobiographical memory recall: the response time to access a past personal event, the experience of remembering (ratings of memory vividness), the emotional content of a cued memory (ratings of event arousal and valence), and the type of event recalled (ratings of event energy, socialness, and uniqueness). We further explored how cue presentation affected autobiographical memory retrieval by administering cues of similar arousal and valence levels in a blocked fashion to one half of the tested participants, and randomly to the other half. We report three main findings. First, memories were accessed most quickly in response to musical cues that were highly arousing and positive in emotion. Second, we observed a relation between a cue and the elicited memory’s emotional valence but not arousal; however, both the cue valence and arousal related to the nature of the recalled event. Specifically, high cue arousal led to lower memory vividness and uniqueness ratings, but cues with both high arousal and positive valence were associated with memories rated as more social and energetic. Finally, cue presentation impacted both how quickly and specifically memories were accessed and how cue valence affected the memory vividness ratings. The implications of these findings for views of how emotion directs the access to memories and the experience of remembering are discussed.     

Words,shape, visual search and visual working memory in 3‐year‐old children

Do words cue children's visual attention, and if so, what are the relevant mechanisms? Across four experiments, 3‐year‐old children (N = 163) were tested in visual search tasks in which targets were cued with only a visual preview versus a visual preview and a spoken name. The experiments were designed to determine whether labels facilitated search times and to examine one route through which labels could have their effect: By influencing the visual working memory representation of the target. The targets and distractors were pictures of instances of basic‐level known categories and the labels were the common name for the target category. We predicted that the label would enhance the visual working memory representation of the target object, guiding attention to objects that better matched the target representation. Experiments 1 and 2 used conjunctive search tasks, and Experiment 3 varied shape discriminability between targets and distractors. Experiment 4 compared the effects of labels to repeated presentations of the visual target, which should also influence the working memory representation of the target. The overall pattern fits contemporary theories of how the contents of visual working memory interact with visual search and attention, and shows that even in very young children heard words affect the processing of visual information.     

Exploration and choice by mice among nest boxes differing in size: Influence of the inner and the outer dimensions

The size of nest boxes induces contrasting effects on exploratory behaviour and nest establishment of mice. Nest box exploration increases, and preference for nest site decreases, with increasing nest box size (Buhot, 1987). The aim of the present study was to continue the investigation of the different effects of the inner vs outer properties (here sizes) of nest boxes, the former being likely to play a major role in nest establishment, whereas the latter were predicted to be mainly involved in the initial exploratory process. The subjects were cagemate groups of two or three male mice. They were subjected to four ranking tests in which the nest boxes differed in outer size only, or in inner size only, and they either had a roof or did not have one. Among nest boxes with identical inside dimensions, the mice preferentially chose as nest sites those with the largest available outer dimensions; the presence of a roof did not affect this preference. In situations with nest boxes differing only in inner size, opposite preferences were observed, depending on whether or not a roof was present. In the presence of roofed nest boxes, mice's preferences were positively correlated with the size of the boxes. In the unroofed condition, an optimal value was observed around the second smaller inner-spaced nest box. Thus, both inner and outer properties influenced nest box choice. As a roof provides maximum safety, its presence seemed to have allowed choice to be governed by a secondary criterion—the maximum distance between the nest and the entrance. Initial exploration patterns were mainly influenced by the outer characteristics of the nest boxes: the larger the nest boxes were on the outside, the earlier and more frequently they were visited.     

Auditory memory can be object based

Identifying how memories are organized remains a fundamental issue in psychology. Previous work has shown that visual short-term memory is organized according to the object of origin, with participants being better at retrieving multiple pieces of information from the same object than from different objects. However, it is not yet clear whether similar memory structures are employed for other modalities, such as audition. Under analogous conditions in the auditory domain, we found that short-term memories for sound can also be organized according to object, with a same-object advantage being demonstrated for the retrieval of information in an auditory scene defined by two complex sounds overlapping in both space and time. Our results provide support for the notion of an auditory object, in addition to the continued identification of similar processing constraints across visual and auditory domains. The identification of modality-independent organizational principles of memory, such as object-based coding, suggests possible mechanisms by which the human processing system remembers multimodal experiences.     

Mood congruence in childhood and recent autobiographical memory

To improve upon previous methodology, participants in musically induced happy, sad, or neutral moods were asked to recall childhood and recent autobiographical memories in response to pleasant, unpleasant, and neutral word cues. Symmetrical mood-congruent memory effects were observed when events were rated from the perspective of when they actually occurred (i.e., then), because memories rated as being unpleasant then tended to be rated as more pleasant now. Finally, pleasant and unpleasant cue words facilitated retrieval of childhood memories more than did neutral cues. These findings suggest that symmetrical mood congruence can be observed when accounting for such factors as the valence of retrieval cues and the perspective from which experiences are rated, given that memories appear to undergo change in affective labelling.