Short-term retention of words as a function of encoding depth

The traditional short- and long-term storage view of information processing and the levels-of-processing view both discuss the forgetting of information over time. In the traditional stage view, there is loss of at least poorly encoded information across several seconds when the information cannot be rehearsed (e.g., Ricker et al., 2020, Learning, Memory, and Cognition, 46, 60-76). In the levels-of-processing approach, information that is encoded in a shallow manner is lost more quickly over time than deeply-encoded information (Craik & Lockhart, 1972, Journal of Verbal Learning and Verbal Behavior, 11, 671-684.). Previous studies of the depth of encoding, however, have mostly been conducted using delayed tests, so there are few studies directly comparing the rate of forgetting over time for information as a function of different depths of encoding. We manipulated the level of processing with immediate recall in a modified Brown-Peterson task. An effect of the level of processing was robust, but evidence of forgetting across retention intervals was not always observed. When encoding time was curtailed (in Experiments 3 and 4), we found main effects of both the level of processing and the retention interval, but no interaction between the two variables. The results suggest that the depth-of-encoding effect may occur during the initial encoding of items, but without differential forgetting within the range of retention intervals that we examined (0-18 s), in contrast to the suggestion by Craik and Lockhart. Further work is needed to determine whether the depth-of-processing effect would grow over longer intervals.

Effects of Iconicity in Recognition Memory

Iconicity refers to a resemblance between word form and meaning. Previous work has shown that iconic words are learned earlier and processed faster. Here, we examined whether iconic words are recognized better on a recognition memory task. We also manipulated the level at which items were encoded-with a focus on either their meaning or their form-in order to gain insight into the mechanism by which iconicity would affect memory. In comparison with non-iconic words, iconic words were associated with a higher false alarm rate, a lower d' score, and a lower response criterion in Experiment 1. We did not observe any interaction between iconicity and encoding condition. To test the generalizability of these findings, we examined effects of iconicity in a recognition memory megastudy across 3880 items. After controlling for a variety of lexical and semantic variables, iconicity was predictive of more hits and false alarms, and a lower response criterion in this dataset. In Experiment 2, we examined whether these effects were due to increased feelings of familiarity for iconic items by including a familiar versus recollect decision. This experiment replicated the overall results of Experiment 1 and found that participants were more likely to categorize words that they had seen before as familiar (vs. recollected) if they were iconic. Together, these results demonstrate that iconicity has an effect on memory. We discuss implications for theories of iconicity.

Reaction time as an outcome measure during online fear conditioning: Effects of number of trials, age, and levels of processing

Recent studies have shown that fear conditioning experiments can be successfully conducted online. However, there is limited evidence that measures other than subjective ratings of threat expectancy can be collected, which means that online research may not be able to adequately replace laboratory experiments. In the current study, we conducted an online fear conditioning experiment consisting of habituation, acquisition, extinction and 48 h delayed extinction recall using ratings of threat expectancy and conditional stimulus pleasantness, and probe reaction time as outcome measures. The conditional stimuli were categories of words and a levels of processing manipulation explored whether words that were processed at a deeper level during extinction evoked smaller differential threat responses during extinction recall. Although the levels of processing manipulation did not produce a significant outcome, we found that extinction recall was successfully operationalised in our study. Reaction time indicated differential responding during both acquisition and extinction recall, and age of participants was correlated in one of two experiments with differential threat expectancy and reaction time, such that older participants showed better safety learning. The outcomes of this experiment provide multiple novel tools for researchers to explore fear conditioning, especially in an online environment.

Examining levels of processing using verbal & pictorial stimuli with the complex trial protocol in a mock theft scenario

The Complex Trial Protocol (CTP) is an EEG-based Concealed Information Test (CIT). Depth of processing influences memorability where deeper processing increases recollection. The CTP's performance as a function of shallow versus deep levels of processing has not been explored. Two experiments were conducted, one with verbal stimuli and the other with their pictorial referents. In both experiments, participants were randomly assigned to three groups, Innocent Control (Control) condition, Guilty Immediate Shallow Processing (Shallow) condition, and Guilty Immediate Deep Processing (Deep) condition. Shallow and Deep participants from both experiments underwent the same mock theft scenario and all three groups were later exposed to either a verbal (N = 41) or pictorial (N = 43) stimulus on a computer monitor. In the word study, no differences in CIT effect were found between any of the groups. Areas under the curve (AUCs) did not differ from chance (.624 and .679 for Shallow and Deep groups respectively). In the image study, the CIT effect for the Shallow and Deep groups differed from the Control one. The AUCs (.755 and .943 for the Shallow and Deep groups respectively) differed significantly from each other. Levels of Processing (LOP) did not appear to have any bearing on CTP performance when words were used as probes but did have an effect when images were used. The findings may hint at some of the limitations of the CTP and fail to replicate similar experiments, especially when words are used as probes, from the late Peter Rosenfeld's laboratory.

Does depth of processing affect temporal contiguity?

Memory tends to be better when items are processed for their meaning (deep processing) rather than their perceptual features (shallow processing). This levels of processing (LOP) effect is well-replicated and has been applied in many settings, but the mechanisms involved are still not well understood. The temporal contiguity effect (TCE), the finding that recalling one event often triggers recall of another event experienced nearby in time, also predicts memory performance. This effect has given rise to several competing theories with specific contiguity-generating mechanisms related to how items are processed. Therefore, studying how LOP and the TCE interact may shed light on the mechanisms underlying both effects. However, it is unknown how LOP and the TCE interact-various theories make differing predictions. In this preregistered study, we tested predictions of three theoretical explanations: accounts which assume temporal information is automatically encoded, accounts based on a trade-off between item and order information, and accounts which emphasize the importance of strategic control processes. Participants completed an immediate free recall task where they either engaged in deep processing, shallow processing, or no additional task while studying each word. Recall and the TCE were highest for no-task lists and greater for deep than shallow processing. Our results support theories which assume temporal associations are automatically encoded and those which emphasize strategic control processes. Both perspectives should be considered in theory development. These findings also suggest temporal information may contribute to better recall under deeper processing with implications for determining which situations benefit from deep processing.

Gradedness of visual awareness depends on attentional scope: Global perception is more graded than local perception

The gradedness or discreteness of our visual awareness has been debated. Here, we investigate the influence of spatial scope of attention on the gradedness of visual awareness. We manipulated scope of attention using hierarchical letter-based tasks (global: broad scope; local: narrow scope). Participants reported the identity of a masked hierarchical letter either at the global level or at the local level. We measured subjective awareness using the perceptual awareness scale ratings and objective performance. The results indicate more graded visual awareness (lesser slope for the awareness rating curve) at the global level compared to the local level. Graded perception was also observed in visibility ratings usage with global level task showing higher usage of the middle PAS ratings. Our results are in line with the prediction of level of processing hypothesis and show that global/local attentional scope and contextual endogenous factors influence the graded nature of our visual awareness.

Impact of multisensory learning on perceptual and lexical processing of unisensory Morse code

Multisensory learning profits from stimulus congruency at different levels of processing. In the current study, we sought to investigate whether multisensory learning can potentially be based on high-level feature congruency (same meaning) without perceptual congruency (same time) and how this relates to changes in brain function and behaviour. 50 subjects learned to decode Morse code (MC) either in unisensory or different multisensory manners. During unisensory learning, the MC was trained as sequences of auditory trains. For low-level congruent (perceptual) multisensory learning, MC was applied as tactile stimulation to the left hand simultaneously to the auditory stimulation. In contrast, high-level congruent multisensory learning involved auditory training, followed by the production of MC sequences requiring motor actions and thereby excludes perceptual congruency. After learning, group differences were observed within three distinct brain regions while processing unisensory (auditory) MC. Both types of multisensory learning were associated with increased activation in the right inferior frontal gyrus. Multisensory low-level learning elicited additional activation in the somatosensory cortex, while multisensory high-level learners showed a reduced activation in the inferior parietal lobule, which is relevant for decoding MC. Furthermore, differences in brain function associated with multisensory learning was related to behavioural reaction times for both multisensory learning groups. Overall, our data support the idea that multisensory learning is potentially based on high-level features without perceptual congruency. Furthermore, learning of multisensory associations involves neural representations of stimulus features involved in learning, but also share common brain activation (i.e. the right IFG), which seems to serve as a site of multisensory integration.

Visual awareness and the levels of processing hypothesis: A critical review

Does a visual percept emerge to consciousness in a graded manner (i.e. evolving through increasing degrees of clarity), or according to a dichotomous, "all-or-none" pattern (i.e. abruptly transitioning from unawareness to awareness)? The level of processing hypothesis (LoP; B. Windey and A. Cleeremans, 2015) recently proposed a theoretical framework where the transition from unaware to aware visual experience is graded for low-level stimulus representations (i.e. stimulus "energy" or "feature" levels) whereas it is dichotomous for high-level (i.e. the perception of "letters", "words" or "meaning") stimulus perception. Here, we will critically review current behavioral and brain-based evidence on the LoP hypothesis and discuss potential challenges (such as differences in LoP conceptualizations, awareness scale related issues, attentional confounds and divergences on experimental factors or statistical analyses) which might be of use for future research within the field. Overall, the LoP hypothesis is a recent and promising proposal that attempts to integrate divergent evidence on the graded vs. dichotomous emergence of awareness debate. Whereas current evidence validates some of the assumptions proposed by the LoP account, there is still much work to do on both methodological and experimental levels. Future neuroimaging studies might help to disentangle the current complex pattern of results found in LoP studies and, importantly, shed some light on the ongoing debate about the search for the Neural Correlates of Consciousness (NCC).

Shades of Awareness on the Mechanisms Underlying the Quality of Conscious Representations: A Commentary to Fazekas and Overgaard ()

Fazekas and Overgaard () present a novel, multidimensional model that explains different ways in which conscious representations can be degraded. Moreover, the authors discuss possible mechanisms that underlie different kinds of degradation, primarily those related to attentional processing. In this letter, we argue that the proposed mechanisms are not sufficient. We propose that (1) attentional mechanisms work differently at various processing stages; and (2) factors that are independent of attentional ones, such as expectation, previous experience, and context, should be accounted for if we are aiming to construct a comprehensive model of conscious visual perception.

A Multi-Factor Account of Degrees of Awareness

In this paper we argue that awareness comes in degrees, and we propose a novel multi-factor account that spans both subjective experiences and perceptual representations. At the subjective level, we argue that conscious experiences can be degraded by being fragmented, less salient, too generic, or flash-like. At the representational level, we identify corresponding features of perceptual representations-their availability for working memory, intensity, precision, and stability-and argue that the mechanisms that affect these features are what ultimately modulate the degree of awareness. We conclude the paper by demonstrating why the original interpretations of certain empirical findings that apparently pose problems for our account are, in fact, flawed.

The drawing effect: Evidence for reliable and robust memory benefits in free recall

In 7 free-recall experiments, the benefit of creating drawings of to-be-remembered information relative to writing was examined as a mnemonic strategy. In Experiments 1 and 2, participants were presented with a list of words and were asked to either draw or write out each. Drawn words were better recalled than written. Experiments 3-5 showed that the memory boost provided by drawing could not be explained by elaborative encoding (deep level of processing, LoP), visual imagery, or picture superiority, respectively. In Experiment 6, we explored potential limitations of the drawing effect, by reducing encoding time and increasing list length. Drawing, relative to writing, still benefited memory despite these constraints. In Experiment 7, the drawing effect was significant even when encoding trial types were compared in pure lists between participants, inconsistent with a distinctiveness account. Together these experiments indicate that drawing enhances memory relative to writing, across settings, instructions, and alternate encoding strategies, both within- and between-participants, and that a deep LoP, visual imagery, or picture superiority, alone or collectively, are not sufficient to explain the observed effect. We propose that drawing improves memory by encouraging a seamless integration of semantic, visual, and motor aspects of a memory trace.

Inert gas narcosis disrupts encoding but not retrieval of long term memory

Exposure to increased ambient pressure causes inert gas narcosis of which one symptom is long-term memory (LTM) impairment. Narcosis is posited to impair LTM by disrupting information encoding, retrieval (self-guided search), or both. The effect of narcosis on the encoding and retrieval of LTM was investigated by testing the effect of learning-recall pressure and levels of processing (LoP) on the free-recall of word lists in divers underwater. All participants (n=60) took part in four conditions in which words were learnt and then recalled at either low pressure (1.4-1.9atm/4-9msw) or high pressure (4.4-5.0atm/34-40msw), as manipulated by changes in depth underwater: low-low (LL), low-high(LH), high-high (HH), and high-low (HL). In addition, participants were assigned to either a deep or shallow processing condition, using LoP methodology. Free-recall memory ability was significantly impaired only when words were initially learned at high pressure (HH & HL conditions). When words were learned at low pressure and then recalled at low pressure (LL condition) or high pressure (LH condition) free-recall was not impaired. Although numerically superior in several conditions, deeper processing failed to significantly improve free-recall ability in any of the learning-recall conditions. This pattern of results support the hypothesis that narcosis disrupts encoding of information into LTM, while retrieval appears to be unaffected. These findings are discussed in relation to similar effects reported by some memory impairing drugs and the practical implications for workers in pressurised environments.