Geometric analogue of holographic reduced representation

Holographic reduced representations (HRRs) are distributed representations of cognitive structures based on superpositions of convolution-bound n-tuples. Restricting HRRs to n-tuples consisting of ±1, one reinterprets the variable binding as a representation of the additive group of binary n-tuples with addition modulo 2. Since convolutions are not defined for vectors, the HRRs cannot be directly associated with geometric structures. Geometric analogues of HRRs are obtained if one considers a projective representation of the same group in the space of blades (geometric products of basis vectors) associated with an arbitrary n-dimensional Euclidean (or pseudo-Euclidean) space. Switching to matrix representations of Clifford algebras, one can always turn a geometric analogue of an HRR into a form of matrix distributed representation. In typical applications the resulting matrices are sparse, so that the matrix representation is less efficient than the representation directly employing the rules of geometric algebra. A yet more efficient procedure is based on ‘projected products’, a hierarchy of geometrically meaningful n-tuple multiplication rules obtained by combining geometric products with projections on relevant multivector subspaces. In terms of dimensionality the geometric analogues of HRRs are in between holographic and tensor-product representations.     

Filling in the Gaps: False Memories and Partisan Bias

While cognitive psychologists have learned a great deal about people's propensity for constructing and acting on false memories, the connection between false memories and politics remains understudied. If partisan bias guides the adoption of beliefs and colors one's interpretation of new events and information, so too might it prove powerful enough to fabricate memories of political circumstances. Across two studies, we first distinguish false memories from false beliefs and expressive responses; false political memories appear to be genuine and subject to partisan bias. We also examine the political and psychological correlates of false memories. Nearly a third of respondents reported remembering a fabricated or factually altered political event, with many going so far as to convey the circumstances under which they “heard about” the event. False-memory recall is correlated with the strength of partisan attachments, interest in politics, and participation, as well as narcissism, conspiratorial thinking, and cognitive ability.     

How accurate are memories of traffic accidents? Increased false memory levels among motorcyclists when confronted with accident-related word lists

Previous studies have found that false memories increase when people receive stimuli which is related to their knowledge base. In the current set of four experiments, we examined how accident experience affected false memory production among motorcyclists using different types of false memory word lists. Specifically, Experiments 1, 2, and 3 were conducted involving motorcyclists with and without accident experience, whereas Study 4 was conducted on non-motorcyclists without accident experience. In all experiments, participants were given associatively-related word lists known to foster false memory creation. Different types of word lists were used consisting of accident-related words, emotionally-negative words, and neutral words. Levels of false memory were measured using recall and recognition tests. We found consistent results in Experiments 1, 2, and 3 in which among motorcyclists, accident-related words produced higher levels of false memory than emotionally-negative and neutral words. This pattern was not observed in Experiment 4 where non-motorcyclists were involved. Our results shed light on the role of previous experience on false memory formation. One implication could be that the police should be careful with reports of motorcyclists' experiences about their accidents as motorcyclists may spontaneously come up with false, but related details concerning these experiences.     

“That one makes things small”: Experimentally induced spontaneous memories in 3.5-year-olds

We introduce a new method for examining spontaneous (unprompted) autobiographical memories in 3.5-year-old children, by inducing them in a laboratory setting. Thirty-eight 3.5-year-olds, who had previously participated in a study in our lab involving highly unique props, were brought back after a one-month delay to the same lab arranged as in the original study and with the same Experimenter present. While waiting for the Experimenter in front of the props, their spontaneous verbalizations about the previous unique experiment were recorded, scored, and compared to those of 29 naïve Controls of the same age. The children in the experimental group produced significantly more spontaneous verbalizations related to the to-be-remembered event measured on a variety of dimensions. The study introduces a promising new approach to investigating spontaneous memories in young children in a controlled lab setting. The findings are discussed in relation to involuntary autobiographical memories as examined in adults.     

True and intentionally fabricated memories

The aim of the experiment reported here was to investigate the processes underlying the construction of truthful and deliberately fabricated memories. Properties of memories created to be intentionally false (fabricated memories) were compared to properties of memories believed to be true (true memories). Participants recalled and then wrote or spoke true memories and fabricated memories of everyday events. It was found that true memories were reliably more vivid than fabricated memories and were nearly always recalled from a first-person perspective. In contrast, fabricated differed from true memories in that they were judged to be reliably older, were more frequently recalled from a third-person perspective, and linguistic analysis revealed that they required more cognitive effort to generate. No notable differences were found across modality of reporting. Finally, it was found that intentionally fabricated memories were created by recalling and then “editing” true memories. Overall, these findings show that true and fabricated memories systematically differ, despite the fact that both are based on true memories.     

When we feel good and bad about ourselves: Self-esteem memories across cultures

Young adults in the United States, Croatia, and China described personal episodes of times when they felt especially good or bad about themselves. These self-esteem memories were either recent (episodes that occurred during the previous 4 weeks) or remote (episodes that occurred between the ages of 10 and 15). Systematic content differences between memories of positive and negative self-worth were apparent primarily for remote rather than for recent memories. Across cultures, long-lasting positive memories frequently represented achievement themes, whereas negative memories frequently represented social themes. Links between achievement success and positive self-regard, and between social distress and negative self-regard, are explained using theories of self-esteem and autobiographical memory.     

The influence of partial‐match cues on event‐based prospective memory

In event‐based prospective memory tasks people form an intention to respond when an environmental cue signals that conditions are appropriate to fulfil an intended activity. In the ongoing activity the authors embedded partial‐match cues that only partially, but not completely, satisfied the conditions required to make a prospective response. The consequence of encountering these partial‐match cues was to increase responses to appropriate prospective memory cues encountered later. This outcome occurred both with semantic and orthographic cues, but only the former led to longer processing latencies of the partial‐match cues. This asymmetry suggests that partial‐match cues may not need to be processed consciously in order to benefit event‐based prospective memory. A parametric manipulation of the number of partial‐match cues resulted in numerically but not statistically better prospective memory. Consequently, partial‐match cues may function as overt reminders of the intention to respond or they may serve to engage participants in self‐initiated remindings of the intention.     

Belief in memories may be relinquished as often for adulthood as for childhood events,but for different reasons

ABSTRACT

The age distribution of nonbelieved memories (NBMs) reported by young and older adults typically reflects a large proportion of events dated to childhood. The present study aimed to further investigate the age of origin of NBMs by using instructions that include an NBM related to adulthood. Participants aged from 40 to 80 years were asked to describe an NBM, to explain why they had stopped believing their memory, and to rate its phenomenal characteristics. Participants also described and rated an age-matched believed memory (BM). The results revealed a similar proportion of nonbelieved events experienced in childhood and adulthood, thus calling into question the hypothesis that NBMs are mainly related to childhood events. We also found that NBMs might emerge for different reasons depending on the time of events. Additional analyses indicated that, overall, the influence of temporal distance on the ratings of phenomenal characteristics was similar for BMs and NBMs.     

Involuntary autobiographical memories in dysphoric mood: A laboratory study

The frequency and characteristics of involuntary autobiographical memories were compared in 25 stable dysphoric and 28 non-dysphoric participants, using a new laboratory-based task (Schlagman & Kvavilashvili, 2008). Participants detected infrequent target stimuli (vertical lines) in a simple vigilance task and recorded any involuntary autobiographical memories that came to mind, mostly in response to irrelevant words presented on the screen. Dysphoric participants reported involuntary memories as frequently and as quickly as non-dysphoric participants and their memories were not repetitive intrusive memories of negative or traumatic events. Additional content analysis showed that dysphoric participants did not recall more memories of objectively negative events (e.g., accidents, illnesses, deaths) than non-dysphoric participants. However, significant group differences emerged in terms of a mood congruency effect whereby dysphoric participants rated their memories as more negative than non-dysphoric participants. Moreover, the proportion of negatively rated involuntary memories was related to lower mood ratings at the end of the session in the dysphoric but not in the non-dysphoric group. Finally, groups did not differ on several memory characteristics such as vividness, specificity (high in both groups) and rates of rehearsal (low in both groups). Theoretical and practical implications of these findings for research on depression and autobiographical memory are discussed.