Marina C. Wimmer

Valence and the development of immediate and long-term false memory illusions

Across five experiments we examined the role of valence in childrens and adults’ true and false memories. Using the Deese/Roediger-McDermott paradigm and either neutral or negative-emotional lists, both adults’ (Experiment 1) and childrens (Experiment 2) true recall and recognition was better for neutral than negative items, and although false recall was also higher for neutral items, false recognition was higher for negative items. The last three experiments examined adults’ (Experiment 3) and childrens (Experiments 4 and 5) 1-week long-term recognition of neutral and negative-emotional information. The results replicated the immediate recall and recognition findings from the first two experiments. More important, these experiments showed that although true recognition decreased over the 1-week interval, false recognition of neutral items remained unchanged whereas false recognition of negative-emotional items increased. These findings are discussed in terms of theories of emotion and memory as well as their forensic implications.

The role of associative strength in children's false memory illusions.

The effects of associative strength on rates of 7- and 11-year-old childrens true and false memories were examined when category and Deese-Roediger-McDermott (DRM) lists were used to cue the same critical lure. Backward associative strength (BAS) was varied such that the category and DRM lists had the same strength (DRM=category), DRM lists had more BAS (DRM>category), or category lists had more BAS (DRM<category). If BAS drives childrens false memories then BAS, not the type of relation across items in a list, should determine false memory production. The results confirmed this prediction using both recall and recognition measures: (1) both true and false memories increased with age, (2) true memory was better for category than DRM lists but there were no differences for false memory, and (3) at all ages, false memories varied predictably with changes in BAS but were unaffected by list-type manipulations. These findings are discussed in the context of models of false memory development.

The development of automatic associative processes and children’s false memories

We investigated childrens ability to generate associations and how automaticity of associative activation unfolds developmentally. Children generated associative responses using a single associate paradigm (Experiment 1) or a Deese/Roediger-McDermott (DRM)-like multiple associates paradigm (Experiment 2). The results indicated that childrens ability to generate meaningful word associates, and the automaticity with which they were generated, increased between 5, 7, and 11 years of age. These findings suggest that childrens domain-specific knowledge base and the associative connections among related concepts are present and continue to develop from a very early age. Moreover, there is an increase in how these concepts are automatically activated with age, something that results from domain-general developments in speed of processing. These changes are consistent with the neurodevelopmental literature and together may provide a more complete explanation of the development of memory illusions.

The development of automatic and controlled inhibitory retrieval processes in true and false recall

In three experiments, we investigated the role of automatic and controlled inhibitory retrieval processes in true and false memory development in children and adults. Experiment 1 incorporated a directed forgetting task to examine controlled retrieval inhibition. Experiments 2 and 3 used a part-set cue and retrieval practice task to examine automatic retrieval inhibition. In the first experiment, the forget cue had no effect on false recall for adults but reduced false recall for children. In Experiments 2 and 3, both tasks caused retrieval impairments for true and false recall, and this occurred for all age groups. Implicit inhibition, which occurs outside of our conscious control, appears early in childhood. However, because young children do not process false memories as automatically as adults, explicit inhibition can reduce false memory output.

Children with autism's perception and understanding of ambiguous figures: Evidence for pictorial metarepresentation, a research note

A large body of autism research over the last 20 years has shown that people with autism have difficulties understanding mental states. This has been conceived of as a metarepresentational deficit. An open question is whether people with autisms metarepresentational deficit is limited to the mental domain. This research explores individuals with autisms understanding of the representational nature of pictures. With the use of ambiguous figures, where a single stimulus is capable of representing two distinct referents, we compared metarepresentational abilities in the pictorial and mental domains and the perception of pictorial ambiguity. Our findings indicate that individuals with autism are impaired in mental metarepresentation but not in pictorial metarepresentation. These findings suggest that children with autism understand the representational nature of pictures. We conclude that children with autisms understanding of the representational nature of pictures is in advance of their metarepresentational understanding of mind. Their perception of figure ambiguity is comparable to the typical population.

How Visuo-Spatial Mental Imagery Develops: Image Generation and Maintenance

Two experiments examined the nature of visuo-spatial mental imagery generation and maintenance in 4-, 6-, 8-, 10-year old children and adults (N = 211). The key questions were how image generation and maintenance develop (Experiment 1) and how accurately children and adults coordinate mental and visually perceived images (Experiment 2). Experiment 1 indicated that basic image generation and maintenance abilities are present at 4 years of age but the precision with which images are generated and maintained improves particularly between 4 and 8 years. In addition to increased precision, Experiment 2 demonstrated that generated and maintained mental images become increasingly similar to visually perceived objects. Altogether, findings suggest that for simple tasks demanding image generation and maintenance, children attain adult-like precision younger than previously reported. This research also sheds new light on the ability to coordinate mental images with visual images in children and adults.

Process dissociation of familiarity and recollection in children: Response deadline affects recollection but not familiarity

According to dual-process theories, recollection (slow and associated with contextual details) and familiarity (fast and automatic) are two independent processes underlying recognition memory. An adapted version of the process dissociation paradigm was used to measure recognition memory in 5-, 7-, and 11-year-olds and adults. In Experiment 1, it was found that 5-year-olds already recollect details of items (i.e., number). Recollection increased particularly between 5 and 7 years. Familiarity differed between 5 years and adulthood. In Experiment 2, under limited response time during retrieval, recollection was eliminated in 5-year-olds and reduced across all ages, whereas familiarity was left unaffected. Together, these findings are consistent with dual-process theories of recognition memory and provide support for two processes underlying recognition memory from a developmental perspective.

Similar but separate systems underlie perceptual bistability in vision and audition

The dynamics of perceptual bistability, the phenomenon in which perception switches between different interpretations of an unchanging stimulus, are characterised by very similar properties across a wide range of qualitatively different paradigms. This suggests that perceptual switching may be triggered by some common source. However, it is also possible that perceptual switching may arise from a distributed system, whose components vary according to the specifics of the perceptual experiences involved. Here we used a visual and an auditory task to determine whether individuals show cross-modal commonalities in perceptual switching. We found that individual perceptual switching rates were significantly correlated across modalities. We then asked whether perceptual switching arises from some central (modality-) task-independent process or from a more distributed task-specific system. We found that a log-normal distribution best explained the distribution of perceptual phases in both modalities, suggestive of a combined set of independent processes causing perceptual switching. Modality- and/or task-dependent differences in these distributions, and lack of correlation with the modality-independent central factors tested (ego-resiliency, creativity, and executive function), also point towards perceptual switching arising from a distributed system of similar but independent processes.

Ego depletion in visual perception: Ego-depleted viewers experience less ambiguous figure reversal

This study examined the effects of ego depletion on ambiguous figure perception. Adults (N = 315) received an ego depletion task and were subsequently tested on their inhibitory control abilities that were indexed by the Stroop task (Experiment 1) and their ability to perceive both interpretations of ambiguous figures that was indexed by reversal (Experiment 2). Ego depletion had a very small effect on reducing inhibitory control (Cohen’s d = .15) (Experiment 1). Ego-depleted participants had a tendency to take longer to respond in Stroop trials. In Experiment 2, ego depletion had small to medium effects on the experience of reversal. Ego-depleted viewers tended to take longer to reverse ambiguous figures (duration to first reversal) when naïve of the ambiguity and experienced less reversal both when naïve and informed of the ambiguity. Together, findings suggest that ego depletion has small effects on inhibitory control and small to medium effects on bottom-up and top-down perceptual processes. The depletion of cognitive resources can reduce our visual perceptual experience.

Are developments in mental scanning and mental rotation related

The development and relation of mental scanning and mental rotation were examined in 4-, 6-, 8-, 10-year old children and adults (N = 102). Based on previous findings from adults and ageing populations, the key question was whether they develop as a set of related abilities and become increasingly differentiated or are unrelated abilities per se. Findings revealed that both mental scanning and rotation abilities develop between 4- and 6 years of age. Specifically, 4-year-olds showed no difference in accuracy of mental scanning and no scanning trials whereas all older children and adults made more errors in scanning trials. Additionally, the minority of 4-year-olds showed a linear increase in response time with increasing rotation angle difference of two stimuli in contrast to all older participants. Despite similar developmental trajectories, mental scanning and rotation performances were unrelated. Thus, adding to research findings from adults, mental scanning and rotation appear to develop as a set of unrelated abilities from the outset. Different underlying abilities such as visual working memory and spatial coding versus representing past and future events are discussed.