Implicit and Explicit Memory in Depression/ Dysphoria: an Analysis of the Contribution of Perceptual and Conceptual Processes

<p>Earlier studies have shown impaired explicit test and normal implicit test performance in participants classified as depressed. A number of different models have been put forward to explain this 'typical' test dissociation including the memory systems, processing, and activation - elaboration models. Blaxton (1989, 1992) has pointed out that to date most test designs have confounded the memory systems and processing models. The aim of this series of experiments was to systematically compare the effects of depression on the processing and memory systems models and in so doing provide a more precise explanation for the effects of depression on human memory. Across Experiments 1 - 4 the performance of participants with depression or dysphoria were examined on implicit and explicit memory tests which were designed to tap either predominantly perceptual or conceptual processes. In Experiment 1 the conceptual tests of category association (implicit) and semantic cued recall (explicit) were compared with the perceptual tests of word fragment completion (implicit) and graphemic cued recall (explicit). In Experiment 2 the perceptual tests of perceptual identification (implicit) and the 'mixed' test of anagram solution (implicit) were compared with the conceptual free recall test (explicit). Both experiments used dysphoric university students and found no effects of dysphoria in comparison to normal controls matched for age, sex and education levels. Experiment 3 compared the conceptual category association (implicit) and free recall (explicit) tests with the perceptual word fragment completion test (implicit) using participants diagnosed with major depression disorder. This revealed significant impairments in both the conceptual tests while the perceptual test was intact. Experiment 4 compared the implicit word association test with the explicit word association test using dysphoric university students. Experiment 4 found that dysphoric participants were impaired in performing the explicit test while the implicit test remained intact. These findings suggest that dysphoria has no effect on implicit tests, but can effect conceptual explicit test measures. Clinical depression effects both conceptual implicit and conceptual explicit test measures. While these results support aspects of both the memory systems and processing models these findings may be best accommodated by a model which combines these models. The revised memory systems model is discussed as one means of achieving this.</p>

Implicit and Explicit Memory in Depression/ Dysphoria: an Analysis of the Contribution of Perceptual and Conceptual Processes

<p>Earlier studies have shown impaired explicit test and normal implicit test performance in participants classified as depressed. A number of different models have been put forward to explain this 'typical' test dissociation including the memory systems, processing, and activation - elaboration models. Blaxton (1989, 1992) has pointed out that to date most test designs have confounded the memory systems and processing models. The aim of this series of experiments was to systematically compare the effects of depression on the processing and memory systems models and in so doing provide a more precise explanation for the effects of depression on human memory. Across Experiments 1 - 4 the performance of participants with depression or dysphoria were examined on implicit and explicit memory tests which were designed to tap either predominantly perceptual or conceptual processes. In Experiment 1 the conceptual tests of category association (implicit) and semantic cued recall (explicit) were compared with the perceptual tests of word fragment completion (implicit) and graphemic cued recall (explicit). In Experiment 2 the perceptual tests of perceptual identification (implicit) and the 'mixed' test of anagram solution (implicit) were compared with the conceptual free recall test (explicit). Both experiments used dysphoric university students and found no effects of dysphoria in comparison to normal controls matched for age, sex and education levels. Experiment 3 compared the conceptual category association (implicit) and free recall (explicit) tests with the perceptual word fragment completion test (implicit) using participants diagnosed with major depression disorder. This revealed significant impairments in both the conceptual tests while the perceptual test was intact. Experiment 4 compared the implicit word association test with the explicit word association test using dysphoric university students. Experiment 4 found that dysphoric participants were impaired in performing the explicit test while the implicit test remained intact. These findings suggest that dysphoria has no effect on implicit tests, but can effect conceptual explicit test measures. Clinical depression effects both conceptual implicit and conceptual explicit test measures. While these results support aspects of both the memory systems and processing models these findings may be best accommodated by a model which combines these models. The revised memory systems model is discussed as one means of achieving this.</p>

Filthiness of Immorality: Manipulating Disgust and Moral Rigidity Through Noninvasive Brain Stimulation as a Promising Therapeutic Tool for Obsessive Compulsive Disorder

The study was designed to test the hypothesis that indirect inhibition of the insula via cathodal transcranial direct current stimulation (tDCS) would decrease disgust and moral rigidity in 36 healthy individuals undergoing 15 min of tDCS over the temporal lobe. To obtain a comprehensive assessment of disgust, we used subjective (affect rating), physiological (heart rate variability [HRV]), and implicit measures (word-fragment completion), and moral judgment was assessed by asking participants to rate the deontological and altruistic moral wrongness of a revised version of the moral foundations vignettes. We found anodal and cathodal stimulations to, respectively, enhance and decrease self-reported disgust, deontological morality, and HRV. Note that these effects were stronger in individuals with higher levels of obsessive compulsive (OC) traits. Because disgust and sensitivity to deontological guilt are among the most impairing features in OC disorder, it is auspicious that cathodal tDCS could be implemented to reduce such symptoms.

PRIMING EFFECTS FOR THE UNEXPECTED STIMULUS IN INATTENTIONAL BLINDNESS

Studies on inattentional blindness demonstrate that a stimulus that unexpectedly appears in the visual environment may be undetected when attention is engaged in a task. The stimulus can still be processed and remembered at the perceptual and semantic level. The question of whether this is still the case when there are items to be ignored in the visual environment remains. In the present study investigating this question, participants attended to furniture pictures while they ignored other pictures. In the inattention trial, an unexpected word appeared in the middle of the circular display. Participants blind to the word were compared to ones who were not exposed to the word. In Experiment 1, participants were more likely to complete a word fragment with this word than the ones who were not exposed to the word. In Experiment 2, participants were more likely to choose the picture of this word than the ones who were not exposed to the word. These studies show that the undetected unexpected stimulus is processed at the perceptual and semantic level and produces priming effects on a subsequent task. Findings were discussed with regards to the possible memory correlates of undetected visual information and levels of consciousness. Keywords: inattentional blindness, priming, consciousness, perceptual processing, semantic processing

Suppression of Non-Selected Meanings Via Hippocampal Inhibition as a Possible Brain Mechanism For Ambiguity Resolution: An fMRI Study Using The Word Fragment Completion Task

Dealing with ambiguity, one usually selects one meaning unconsciously and remains unaware of the alternative meanings. The brain systems dealing with multiple meanings of ambiguous stimuli are relatively well studied, while the brain processing of their non-selected meanings is relatively less investigated. The current functional MRI event-related study used a modified version of the word fragment completion task to reveal possible brain mechanisms involved in processing the non-selected meaning of ambiguous stimuli. Some noun stimuli were ambiguous, and the others were not. Adjectives created contexts strongly biasing the choice of the noun meaning in one or the other way. All ambiguous and unambiguous noun stimuli were presented twice during the experiment. It was revealed that ambiguity resolution was associated with a decrement in the BOLD signal within the right and left hippocampi. This finding supported one of the tested hypotheses assumed that non-selected meanings are actively suppressed. The similarity between this result and BOLD signal changes observed for suppression-induced forgetting for purging unwanted memories from awareness allows suggesting the general neurophysiological basis for voluntary and automatic inhibitory awareness control.

The Influence of LED Lighting on Attention and Long-Term Memory

The fact that the illuminance of LED lights affects human attention and long-term memory has been verified through various studies, but there are no consistent research results about what level of illuminance is effective. The aims of this study were to systematically verify the effects of LED lighting on attention and long-term memory. The experiment was designed with four illuminance levels—300 lx, 400 lx, 500 lx, and 1,000 lx—as experimental conditions to determine the effects of LED lights on attention and long-term memory. Participants in the experiment were 18 college students. The attention task was performed using a handmade attention measuring instrument. Long-term memory was measured by the word fragment completion (hereinafter, referred to as “WFC”) task on the memory retention volume of the learning task that was learned exactly 24 hours before. Of the total 20 tasks, the ratio of correctly retrieval tasks was used as a dependent variable. As a result, attention showed the highest performance with a mean performance of 19.39 (SD = 3.78) at 1,000 lx. A statistically significant difference was also found between the 1,000 lx and 300 lx conditions (p=0.01). On the contrary, long-term memory showed the highest retrieval rate at an average of 58.06% (SD = 22.57) at 400 lx, and long-term memory performance was better in the order of 500 lx (mean = 48.89, SD = 20.33), 1,000 lx (mean = 45.83, SD = 23.53), and 300 lx (Mean = 43.33, SD = 19.10). Statistically, there was a significant difference between 300 lx and 400 lx (p=0.01), 400 lx and 1,000 lx (p=0.01). Through this study, it was verified that the effects of attention and long-term memory are different according to the illuminance of LED lighting, and these results can be important data to clarify the influence of light on human memory in the future.

The Generation Effect Revisited: Fewer Generation Constraints Enhances Item and Context Memory

Self-generated information is often better remembered than non-self-generated information. This effect has been robust for item memory (i.e., the content of information) across many different experiments, but inconsistent for context memory (e.g., memory for the extraneous details of information, such as source). Previous studies examining the generation effect, however, have often applied constraints on the generation task possibly limiting the memory benefit from self-generation. In three experiments, we compared item and context memory for a lower-constraint generation task (i.e., free response to a cue word) relative to higher-constraint generation tasks (Exp. 1 &amp; 2: scramble; Exp. 3: word fragment). Results showed that participants had better item and context memory in the lower-constraint compared to higher-constraint generation tasks. Overall, these experiments suggest that that the mnemonic benefits of self-generation depend on the level of task constraint. This study further advances the idea that self-generation is a powerful mnemonic that leads to enriched memory representations for both the item and context, especially when fewer generation constraints are imposed.

Guns Automatically Prime Aggressive Thoughts, Regardless of Whether a “Good Guy” or “Bad Guy” Holds the Gun

The mere presence of weapons can increase aggression—called the “weapons effect.” Weapons are theorized to increase aggression by priming aggressive thoughts. This research tested the robustness of the weapons effect using two large representative samples of American adults (total N = 1,097). Participants saw photos of criminals, soldiers, police in military gear, or police in regular gear with guns. Experiment 2 also included a condition with photos of Olympians with guns used to shoot inanimate targets. The control group was police in plainclothes without guns. The accessibility of aggressive thoughts was measured using a word fragment task (e.g., KI_ _ can be completed as KILL or KISS). Photos of individuals with guns used to shoot human targets primed aggressive thoughts, regardless of whether a “good guy” (soldier, police) or “bad guy” (criminal) held the gun. Photos of Olympians with guns used to shoot inanimate targets did not prime aggressive thoughts.