Recall Latencies, Confidence, and Output Positions of True and False Memories: Implications for Recall and Metamemory Theories

Recall latency, recall accuracy rate, and recall confidence were examined in free recall as a function of recall output serial position using a modified Deese-Roediger-McDermott paradigm to test a strength-based theory against the dual-retrieval process theory of recall output sequence. The strength theory predicts the item output sequence to be in the descending order of memory strength. The dual-retrieval process theory postulates two phases in a free recall, a first direct access phase in which items are output verbatim in the weakest-to-strongest order (cognitive triage) and a second reconstructive phase in which reconstructed items are output in the strongest-to-weakest order. In four experiments, all three indicators of memory strength (latency, accuracy, and confidence) consistently showed a descending-strength order of recall both for true and false memories. Additionally, false memory was found to be output in two phases and subjects\u27 confidence judgment of their own memory to be unaccountable by retrieval fluency (recall latency)

Editorial: The Depth and Complexity of Unconscious Processing

The study of unconscious information processing mechanism is very important to the development of the science of human consciousness. By studying unconscious processing and comparing it with consciousness processing, we can better understand the ways unconsciousness works and the origin of conscious processing. The scope and limitations of unconscious processing have been discussed for more than a century, but no consensus has been reached for a long time. Some researchers believe that the scope of information that unconscious processing can reach is very limited, and only simple stimuli can be processed unconsciously, while others believe that any types of information can be processed unconsciously. Although the hypothesis that the scope of unconscious processing is equivalent to that of the conscious processing remains to be verified, with the deepening of the study of the unconsciousness, the idea that unconscious processing is limited to simple types of information is questioned. The papers included in this Research Topic “The Depth and Complexity of Unconscious Processing” provide some new evidence with respect to the complexity of unconscious processing. Here, we first present a brief overview of the contents of the present research topic

Pure Partial Awareness or Interaction between the Mask and the Masked Stimuli?

Many studies using masking paradigm have shown that stimuli can be processed unconsciously. However, different researchers put forward different ideas about the mechanisms of the unconscious information processing. For example, one idea is that the unconscious information might be derived from a partial awareness of the masked stimulus. Another idea is that it is derived from a perceptual interaction between a masked stimulus and the masking stimulus. We used a masking paradigm (with a briefly displayed target followed by a mask) and a subjective rating and an objective forced-choice test (with a word and picture version) given after the display to study the nature of partial awareness. The question we attempted to answer was whether people did perceive fragmentary features of a masked object picture correctly when they rated it as partially perceivable. The results showed that even when the masked stimuli only had simple features and when the subjects subjectively reported that they could perceive something of the masked stimuli, the objective forced-choice test performance was at chance level. The results were discussed in the context of interaction hypothesis and level of processing hypothesis

Why are the Trial-By-Trial, Strength-Based Criterion Shifts Hard to Observe? Is the Difficulty in the Mental Process Itself or in the Typical Cued-Criterion Method?

In the cued-criterion recognition paradigm (Stretch & Wixted, 1998a), trial-by-trial memory-strength based criterion shifts have been an elusive phenomenon. Often the criterion shifts fail to occur. We suggest that the frequent failure in making criterion shifts in the literature is due to participants’ failure to understand the rationale of the task as typically presented in an abstract format. In this study, participants studied words once or thrice and were asked at test to either classify the probes into “new”, “seen once”, or “seen 3 times” categories by pressing the corresponding keys, or to make an Old/New binary decision followed by an item presentation-frequency judgment, a confidence, or a memory-quality judgment. No memory-strength cues were provided and only one set of new items served as distractors for strong and weak targets. Robust trial-by-trial criterion shift was observed. We concluded that no cues distinguishing between strong and weak probes are necessary for obtaining this type of criterion shift when the tasks are designed to make good pragmatic sense for the participants. The reason why this type of criterion shifts is typically hard to obtain in the cued-criterion paradigm is not that the process itself is difficult, but that the cued-criterion method is hard to understand to the participants

The impact of social comparison on the neural substrates of reward processing: An event-related potential study

Event-related potentials (ERPs) were recorded to explore the electrophysiological correlates of reward processing in the social comparison context when subjects performed a simple number estimation task that entailed monetary rewards for correct answers. Three social comparison stimulus categories (three relative reward levels/self reward related to the other subject\u27s) were mainly prepared: Self:Other=1:2 (Disadvantageous inequity condition); Self:Other=1:1 (Equity condition); and Self:Other=2:1 (Advantageous inequity condition). Results showed that: both Disadvantageous and Advantageous inequity elicited a more negative ERP deflection (N350–550) than did Equity between 350 and 550 ms, and the generators of N350–550 were localized near the parahippocampal gyrus and the medial frontal/anterior cingulate cortex, which might be related to monitor and control reward prediction error during reward processing. Then, Disadvantageous and Advantageous inequity both elicited a more late negative complex (LNC1 and LNC2) than did Equity between 550 and 750 ms. The generators of LNC1 and LNC2 were both localized near the caudate nucleus, which might be related to reward processing under social comparison

A Target Sequential Effect on the Forced-Choice Prime Visibility Test in Unconscious Priming Studies: A Caveat for Researchers

In unconscious priming studies, most researchers adopt a combination of subjective and objective measures to assess the visibility of the prime. Although some carry out the visibility test at the end of the experiment separately from the unconscious priming task, others suggest that the forced-choice visibility test should be conducted immediately after the response to the target within each trial. In the present study, the influence of prime and target on the forced-choice prime discrimination was assessed within each trial. The results showed that the target affected the response in the forced-choice prime visibility test. Participants tended to make the same response or avoid repeating the same response they made to the target as in Experiments 1 and 3 rather than randomly guessing. However, even when the forcedchoice visibility test was conducted separately from the priming experiment, the problem was not completely solved, because some participants tended to make one same response in the forced-choice visibility test as in Experiments 2. From another point of view, using these strategies in the forced-choice task can be seen as a helpless move by the participants when they are unaware of the stimuli. Furthermore, the results revealed that the forced-choice test performed immediately after the response to the target within each trial could possibly impair the unconscious priming as well as produce misleading visibility test results. Therefore, it is suggested that the forced-choice prime visibility test and the unconscious priming task may better be conducted separately

Unconscious Processing of Facial Emotional Valence Relation: Behavioral Evidence of Integration between Subliminally Perceived Stimuli

Although a few studies have investigated the integration between some types of unconscious stimuli, no research has yet explored the integration between unconscious emotional stimuli. This study was designed to provide behavioral evidence for the integration between unconsciously perceived emotional faces (same or different valence relation) using a modified priming paradigm. In two experiments, participants were asked to decide whether two faces in the target, which followed two subliminally presented faces of same or different emotional expressions, were of the same or different emotional valence. The interstimulus interval (ISI) between the prime and the target was manipulated (0, 53, 163 ms). In Experiment 1, prime visibility was assessed post-experiment. In Experiment 2, it was assessed on each trial. Interestingly, in both experiments, unconsciously processed valence relation of the two faces in the prime generated a negative priming effect in the response to the supraliminally presented target, independent of the length of ISI. Further analyses suggested that the negative priming was probably caused by a motor response incongruent relation between the subliminally perceived prime and the supraliminally perceived target. The visual feature incongruent relation across the prime and target was not found to play a role in the negative priming. Because the negative priming was found at short ISI, an attention mechanism as well as a motor inhibition mechanism were proposed in the generation of the negative priming effect. Overall, this study indicated that the subliminal valence relation was processed, and that integration between different unconsciously perceived stimuli could occur

Category-selective Attention Modulates Unconscious Processing: Evidence from ERP

Aims: Recently, using the fMRI method in a paradigm in which visible word cues were followed by masked faces at a completely unconscious level or masked tools at a partially conscious level, Tu, Qiu, Martens, & Zhang [31] showed that the top-down modulation effects were in opposite directions for the two conditions. Because five different pictures of masked faces/tools were displayed in a trial, the authors proposed that the modulation effects could further interact with the conscious component of the partial awareness processing (i.e., awareness of the global contour change). In the present event-related potential study, we employed a paradigm similar to that of Tu et al.’s [31] except that the masked stimulus was displayed only once to test the effect of category selective attention on unconscious processing of picture identity and to try to investigate the above hypothesis. Study Design: Two semantic category cues (“face” or “tool”) and two types of subliminal stimuli (face or tool images) were crossed to generate four conditions: a face cue followed by a masked face picture, a face cue followed by a masked tool picture, a tool cue followed by a masked face picture, and a tool cue followed by a masked tool picture. Place and Duration of Study: Department of psychology, Institute of education, China West Normal University, between September 2013 and April 2014. Methodology: The technique of event-related potentials (ERP) was used. Results: Processing of masked face and tool images both elicited the ERP components of C1, P1, N1, and P2. In addition, C1 component between 25 ms and 55 ms was smaller in the valid category cue-word condition (face cue-word followed by masked face image & tool cue-word followed by masked tool image) than in the invalid cue-words (face cue-word followed by masked tool image & tool cue-word followed by masked face image). The other three waves, P1, N1, and P2, were found to be unaffected by the top–down modulation Conclusion: Category-selective attention can modulate unconscious processes at an early stage of visual processing supporting the interaction hypothesis

Two paradigms of measuring serial-order memory: two different patterns of serial-position functions

There are two research paradigms in the area of serial-order memory. One typically uses serial recall (accuracy), and the other comparative judgment (reaction time) for measuring serial-order memory. Spontaneous subgrouping is commonly observed in the recall serial-position function in the form of multiple bowings. However, comparative judgment with a reaction time measure produces a single-bowing function. Researchers adopting these two approaches have opposing views on the form of the structure of serial-order memory with the former favoring a hierarchical, and the latter a unidimensional structure. The present study confirmed the above hypothesized relation between the two measuring procedures and the two different patterns of serial-position functions. It was suggested that a serial recall involves retrieving absolute position information, whereas a comparative judgment involves retrieving relative position information, and that subgrouping serves a facilitating function for the former, but may actually impede the latter process