Units of episodic memory in perceptual recognition.

Although the majority of research on human memory has concentrated on a person's ability to recall or recognize items as having been presented in a particular situation, the effects of memory are also revealed in a person's performance of a perceptual task. Prior experience with material can make that material more easily identified or comprehended in perceptually difficult situations. Unlike with standard retention tests, effects of prior experience on a perceptual task do not logically require that a person be aware that he or she is remembering. Indeed, amnesic patients purportedly show effects of practice in their subsequent performance of a perceptual or motor task even though they profess that they do not remember having engaged in that prior experience. The experiments that are reported were designed to explore the relationship between the more aware autobiographical form of memory that is measured by a recognition memory test and the less aware form of memory that is expressed in perceptual learning. Comparisons of effects on perceptual learning and recognition memory reveal two classes of variables. Variables such as the level of processing of words during study influenced recognition memory, although they had no effect on subsequent perceptual recognition. A study presentation of a word had as large an effect on its later perceptual recognition when recognition memory performance was very poor as it did when recognition memory performance was near perfect. In contrast, variables such as the number and the spacing of repetitions produced parallel effects on perceptual recognition and recognition memory. Following Mandler and others, it is suggested that there are two bases for recognition memory. If an item is readily perceived so that it seems to "jump out" from the page, a person is likely to judge that he or she has previously seen the item in the experimental situation. Variables that influence ease of perceptual recognition, then, can also have an effect on recognition memory, so parallel effects are found. The second basis for recognition memory involves elaboration of a word's study context and depends on such factors as level of processing during study--factors that are not important for perceptual recognition of isolated words. Comparisons of perceptual recognition and recognition memory are shown to be useful for determining how a variable has its effect. Effects of study on perceptual recognition appear to be totally due to memory for physical or graphemic information. Results reported are also relevant to theories of perceptual learning. A single presentation of an item is shown to have large and long-lasting effects on its later perceptual recognition. At least partially, effects of study on perceptual recognition depend on the same variables as do effects on more standard memory tests.

Performance on a perceptual recognition task and a concurrently performed short-term memory (STM) task was studied. The stimuli used in the STM task were either visually similar, acoustically similar, or dissimilar to the stimuli in the perceptual task. The results demonstrated that any type of concurrent list memorization has a detrimental effect upon perceptual performance, but this effect is magnified if the stimuli used in the 2 tasks are visually similar. Acoustic similarity had no effect. The results document the fact that distinct tasks interfere, when the tasks compete for a limited total processing capacity, or when the tasks demand the same visual coding program.

This study investigated the relationship between the extent of defensive responding on a perceptual recognition task and score on the Handal death anxiety scale. The results did not confirm the hypothesis that perceptually defensive respondents (those with elevated thresholds for death words as opposed to neutral words) would tend to have lower scores on the death anxiety inventory. Additional research into multilevel criteria of death anxiety is suggested along with improving the internal consistency of the Handal death anxiety scale.

A Developmental Study of the Effects of Pretraining on a Perceptual Recognition Task

The effect of semantic and nonsemantic factors on the integration of verbal units in recognition memory.

Table of Contents E.N. Sokolov (1920-2008) Preface Introduction Part 1. The spherical model of cognitive processing Chapter 1. Vector encoding in perception 1.1. The detector neuron 1.2. The neuronal structure of color space 1.3. Detectors of orientation and spatial frequency 1.4. Detectors of orientation and direction of lines in motion 1.5. Computation of perceptual differences: the perceptual evoked potential Chapter 2. From detector map to maps of memory and semantic units 2.1. The vector code in mismatch negativity 2.2. Recognition memory: vector transformation in neural networks 2.3. Association of memory traces based on time and similarity 2.4. Correlation between percepts and semantics 2.5. Computation of semantic differences in neural networks Chapter 3. Vector encoding in response conditioning 3.1. Synaptic mechanisms of the conditional response 3.2. Corticofugal and centripetal modulation of detector maps 3.3. Fluctuation of the pacemaker potential 3.4. The pacemaker potential in receptors, detectors and command neurons Part 2. The Neural Screen of Consciousness Chapter 4. The modular organization of the brain 4.1. The modular organization of cortical neurons. 4.2. Are all neurons associated with consciousness? 4.3. Consciousness and sleep Chapter 5. The mosaic nature of consciousness 5.1. The concept of distributed consciousness 5.2. Perception 5.3. Memory and semantics 5.4. Emotions 5.5. Subjective mosaics Chapter 6. Varieties of consciousness 6.1. Global and focal changes of consciousness 6.2. Special states of neurons in global and focal loss of consciousness 6.3. Filling-in and assimilation 6.4. Contrast 6.5. Masking 6.6. Supersensitivity Chapter 7. The neurophysiology of consciousness 7.1. Introspective and neuroconceptual models of consciousness 7.2. Re-entry 7.3. Consciousness and rhythmic brain activity 7.4. The gamma-rhythm and consciousness 7.5. Semantic evoked potentials 7.6. Consciousness neurons 7.7. Neurocomputation on dendrites 7.8. The intracellular mechanism of consciousness Conclusion: the spherical model of consciousness Bibliography

Bayesian inference is an effective approach to capture the model uncertainty as well as tackle the over-fitting problem in deep neural networks. Recently Bayesian neural networks (BNNs) are becoming more and more popular and have succeeded in many recognition tasks. However, the BNNs inference procedure requires numerous memory access operations due to the resulted sampling networks. In this paper, a near memory architecture is proposed for accelerating BNN inference by introducing additional memory units near the processing units. The near memory architecture could cache the frequently accessed data to reduce the data movement efficiently. Minimizing the expensive data movements between memory units and computation units contributes to cutting down the latency and energy consumption. Comparing with the traditional approach, the simulation results show that the proposed architecture reduces the energy consumption by 9% and achieves a 1:6 speedup at the cost of 4% area overhead.

The medial temporal lobe (MTL) encompasses a network of interconnected cortical areas that is considered the neural substrate for some types of memory, such as spatial, episodic, recognition, and associative memory. Within the MTL, the subiculum has been well characterized in terms of its connectivity and structure, but its functional role remains elusive. A long-held view is that the subiculum is mainly involved in spatial encoding because it exhibits spatially selective firing and receives prominent projections from the CA1 field, which is an essential substrate for spatial memory. However, the dorsal subiculum (DS) is also reciprocally connected to the perirhinal and postrhinal cortices, which are critically involved in recognition memory. This connectivity pattern suggests that DS might encode not only spatial signals but also recognition signals. Here, we examined this hypothesis by recording with multi-electrodes in DS and CA1 of freely behaving mice, as they performed the novel object recognition (NOR) task. Analysis of network oscillations revealed that theta power was significantly higher in DS when mice explored novel objects as compared to familiar objects and that this theta modulation was absent in CA1. We also found significant differences in coherence between DS and CA1, in the theta and gamma bands, depending on whether mice examined objects or engaged in spatial exploration. Furthermore, single-unit recordings revealed that DS cells did not exhibit phase-locked firing to theta and differed from CA1 place cells in that they had multiple peaks of spatially selective firing. We also detected DS units that were responsive specifically to novel object exploration, indicating that a subset of DS neurons were tuned to novelty during the NOR task. We have thus identified clear neurophysiological correlates for recognition within the DS, at the network and single-unit levels, strongly suggesting that it participates in encoding recognition-related signals.

Context and repetition effects in lexical decision and recognition memory

Semantic and episodic memory in aphasia

This manuscript covers my personal history on the search for the neural circuits supporting early developing memory in primates. A series of developmental neuropsychological studies is presented to follow the successive knowledge we gained over several decades on the timing of development of the hippocampus and hippocampal-dependent recognition memory functions in primates. The borrowing of an incidental recognition memory task measuring novelty preference to infer subjects' memory was central to assessing memory in young infant monkeys of only a few weeks old. Data revealed that the emergence of adult-like proficiency in visual recognition and spatial memory tasks sensitive to hippocampal dysfunction is a stepwise process. This progressive development was associated with the gradual maturation of different hippocampal intrinsic circuits (Entorhinal-CA1 and Entorhinal-Dentate Gyrus-CA fields) and their connections with other cortical structures (the perirhinal, parahippocampal, parietal, and prefrontal cortices). We also showed that a similar postnatal maturation of hippocampal-dependent memory is observed in human infants, suggesting important changes in the role of the hippocampus and medial temporal cortical areas in human memory development as well.

The other-race effect (or own-race bias or cross-racial identification effect) refers to the finding that recognition memory tends to be better for faces of members of subjects' own race than for faces of members of other races. The current study was designed to test the hypothesis that perceptual skills specific to identifying faces of particular racial groups contribute to this effect. On each of 50 trials, a photograph of a face was tachistoscopically presented for 120 ms, followed by a pattern mask and then a plain-view test pair composed of the previously presented face and a matched foil. As predicted, an other-race effect was obtained on this perceptual task: White subjects performed significantly more poorly on trials involving African American faces than on trials involving White faces, whereas no such difference was obtained among African American subjects.

Recent reviews (A.S. Brown & D.B. Mitchell, 1994; B. Challis & D.R. Brodbeck, 1992) concluded that level-of-processing (LOP) manipulations affect priming in perceptual tasks, contrary to earlier suggestions that such tasks are insensitive to LOP. In 3 experiments with amnesic patients and control subjects, the authors examined the effect of LOP manipulations on priming in word-stem and word-fragment completion and on recognition memory. Amnesic patients exhibited reduced or near-zero LOP effects in word-completion priming compared with control subjects. LOP affected recognition memory for both amnesic patients and control subjects, confirming that the LOP manipulation affected explicit memory. When the effect of explicit retrieval on control performance was reduced by using a low-level encoding task, priming was the same for amnesic patients and control subjects. The authors suggest that LOP effects in word-completion priming tasks reflect the influence of explicit retrieval, which can be used usefully by control subjects but much less so by amnesic patients.

Deletion of the GluA1 AMPA receptor subunit impairs short-term spatial recognition memory. It has been suggested that short-term recognition depends upon memory caused by the recent presentation of a stimulus that is independent of contextual–retrieval processes. The aim of the present set of experiments was to test whether the role of GluA1 extends to nonspatial recognition memory. Wild-type and GluA1 knockout mice were tested on the standard object recognition task and a context-independent recognition task that required recency-dependent memory. In a first set of experiments it was found that GluA1 deletion failed to impair performance on either of the object recognition or recency-dependent tasks. However, GluA1 knockout mice displayed increased levels of exploration of the objects in both the sample and test phases compared to controls. In contrast, when the time that GluA1 knockout mice spent exploring the objects was yoked to control mice during the sample phase, it was found that GluA1 deletion now impaired performance on both the object recognition and the recency-dependent tasks. GluA1 deletion failed to impair performance on a context-dependent recognition task regardless of whether object exposure in knockout mice was yoked to controls or not. These results demonstrate that GluA1 is necessary for nonspatial as well as spatial recognition memory and plays an important role in recency-dependent memory processes.

: Short-term episodic visual recognition memory is crucial to success in many everyday activities. We synthesized concepts, insights, and methods from memory research, and from vision research, working within a coherent, quantitative framework for understanding episodic visual recognition memory. Seven experiments were carried out in two related sub-projects. One sub-project confirmed that high-dimensional stimuli (synthetic human faces) afford important insights into episodic recognition memory. The results were well accommodated by a summed similarity theory of recognition memory (Kahana & Sekuler, 2002). The second sub-project supported coordinated experiments on recognition memory and item identification (source memory). Source identification errors were deterministic rather than stochastic, and their causes were identified. Receiver operating characteristics (ROCs) compared recognition across experiments. Combining signal detection theory and a summed similarity model explained the unusual properties of the z-transformed ROCS.