Visual Long-term Memory Research Articles

Scene Memory Is More Detailed Than You Think

Observers can store thousands of object images in visual long-term memory with high fidelity, but the fidelity of scene representations in long-term memory is not known. Here, we probed scene-representation fidelity by varying the number of studied exemplars in different scene categories and testing memory using exemplar-level foils. Observers viewed thousands of scenes over 5.5 hr and then completed a series of forced-choice tests. Memory performance was high, even with up to 64 scenes from the same category in memory. Moreover, there was only a 2% decrease in accuracy for each doubling of the number of studied scene exemplars. Surprisingly, this degree of categorical interference was similar to the degree previously demonstrated for object memory. Thus, although scenes have often been defined as a superset of objects, our results suggest that scenes and objects may be entities at a similar level of abstraction in visual long-term memory.

Examining object representation via object memory: Exemplar and state-level object properties are supported by the same underlying features

The properties of any given image of a real-world object (e.g., a phone) are determined both by the particular exemplar of the category it represents, and by which state or pose the exemplar is in. For example, there are many different kinds of phones (exemplar-level information) and any given phone can be on or off the hook (state-level information). Here, we use an object memory paradigm to examine the separability of these object properties in memory. If object properties can be encoded or decay independently, then we can infer that different high-level features underlie their representations. 12 observers were shown 120 briefly presented objects, and judged the physical size of the objects. Following this task, we gave observers a surprise memory test. To probe which properties of each object were incidentally encoded, a 4-alternative forced choice test display was presented for each object, consisting of two exemplars (one familiar, one novel), each in two states (one familiar, one novel). By modeling these data, we examined how often people remembered only the exemplar-level information or only state-level information. Using both goodness of fit measures and Bayesian model selection, we examined whether the data were better fit by a model in which these kinds of information were represented independently or together. Both methods support a model in which these two types of object information are bound together, suggesting that memory for both exemplar- and state-level object properties is supported by the same underlying high-level visual features. Thus, as both visual long-term memory and object recognition depend on the same high-level object representation, memory errors can usefully inform models of object recognition by elucidating the underlying object representation.

Similar Scenes Seen: What are the limits of the visual long-term memory fidelity?

Similar Scenes Seen: What are the limits of the visual long-term memory fidelity?

Conceptual distinctiveness supports detailed visual long-term memory for real-world objects.

Humans have a massive capacity to store detailed information in visual long-term memory. The present studies explored the fidelity of these visual long-term memory representations and examined how conceptual and perceptual features of object categories support this capacity. Observers viewed 2,800 object images with a different number of exemplars presented from each category. At test, observers indicated which of 2 exemplars they had previously studied. Memory performance was high and remained quite high (82% accuracy) with 16 exemplars from a category in memory, demonstrating a large memory capacity for object exemplars. However, memory performance decreased as more exemplars were held in memory, implying systematic categorical interference. Object categories with conceptually distinctive exemplars showed less interference in memory as the number of exemplars increased. Interference in memory was not predicted by the perceptual distinctiveness of exemplars from an object category, though these perceptual measures predicted visual search rates for an object target among exemplars. These data provide evidence that observers' capacity to remember visual information in long-term memory depends more on conceptual structure than perceptual distinctiveness.

Long-term visual associations affect attentional guidance

When observers perform a visual search task, they are assumed to adopt an attentional set for what they are looking for. The present experiment investigates the influence of long-term visual memory associations on this attentional set. On each trial, observers were asked to search a display for a grayscale version of a known traffic sign. On each trial, a distractor sign was drawn in full color. This color could either be related or unrelated to the target sign. Distractors interfered more with search when their color was related (e.g. red when the target was a stop sign), implying that long-term color associations resulted in inadvertent attentional guidance, even though color was irrelevant to the task. The results add to the growing body of evidence that long-term memory representations automatically affect attentional orienting.

Effects of Viewing Time, Fixations, and Viewing Strategies on Visual Memory for Briefly Presented Natural Objects

We investigated the impact of viewing time and fixations on visual memory for briefly presented natural objects. Participants saw a display of eight natural objects arranged in a circle and used a partial report procedure to assign one object to the position it previously occupied during stimulus presentation. At the longest viewing time of 7,000 ms or 10 fixations, memory performance was significantly higher than at the shorter times. This increase was accompanied by a primacy effect, suggesting a contribution of another memory component-for example, visual long-term memory (VLTM). We found a very limited beneficial effect of fixations on objects; fixated objects were only remembered better at the shortest viewing times. Our results revealed an intriguing difference between the use of a blocked versus an interleaved experimental design. When trial length was predictable, in the blocked design, target fixation durations increased with longer viewing times. When trial length was unpredictable, fixation durations stayed the same for all viewing lengths. Memory performance was not affected by this design manipulation, thus also supporting the idea that the number and duration of fixations are not closely coupled to memory performance.

Object appearance and picture-specific viewpoint are not integrated in long-term memory

Previous work has demonstrated that visual long-term memory (VLTM) stores detailed information about object appearance. The current experiments investigate whether object appearance information in VLTM is integrated within representations that contain picture-specific viewpoint information. In three experiments using both incidental and intentional encoding instructions, participants were unable to perform above chance on recognition tests that required recognizing the conjunction of object appearance and viewpoint information (Experiments 1a, 1b, 2, and 3). However, performance was better when object appearance information (Experiments 1a, 1b, and 2) or picture-specific viewpoint information (Experiment 3) alone was sufficient to succeed on the memory test. These results replicate previous work demonstrating good memory for object appearance and viewpoint. However the current results suggest that object appearance and viewpoint are not episodically integrated in VLTM.

The effect of target detection on visual long-term memory for background scenes

The effect of target detection on visual long-term memory for background scenes

The high fidelity of scene representation in visual long-term memory

The high fidelity of scene representation in visual long-term memory

The invariance of visual long-term memory to geometric transformation

The invariance of visual long-term memory to geometric transformation

Effects of familiarity on visual working memory of upright and inverted faces

Aim: Can we hold more familiar items than novel items in visual working memory (VWM)? Previous studies suggest not: familiar polygons are not remembered more efficiently than novel ones and upright letters are not remembered better than inverted letters. In this study we report an exception to this rule when faces of different familiarity were tested. Methods: Our study was revised from Buttle & Raymond (2003) who tested perception of briefly presented and masked faces. To study VWM rather than perception, we presented faces for a long duration (500ms or several seconds) and inserted a long retention interval (1000ms) in a change detection task. VWM for three types of faces was tested: superfamiliar faces of celebrities or one's friends, moderately familiar faces that had been viewed 160 times before, and novel faces. Subjects held 4 faces in VWM while performing an articulatory suppression task. Results: VWM for superfamiliar upright faces (celebrities or friends) was significantly better than that for novel upright faces, but this enhancement was not observed for recently trained upright faces and was eliminated by the inversion of faces. These results extend the superfamiliarity effect observed by Buttle & Raymond (2003) from a perceptual task to a VWM task. Conclusion: Our study suggests VWM can be influenced by long-term visual memory, but only if the set of items that must be distinguished in VWM are subtly different and that subjects have achieved superfamiliarity with the stimuli.

Interactions between long-term visual working memory and attention

Interactions between long-term visual working memory and attention

Not all visual memories are created equal

Two experiments examined how well the long-term visual memories of objects that are encountered multiple times during visual search are updated. Participants searched for a target two or four times (e.g., white cat) among distractors that shared the target's colour, category, or were unrelated while their eye movements were recorded. Following the search, a surprise visual memory test was given. With additional object presentations, only target memory reliably improved; distractor memory was unaffected by the number of object presentations. Regression analyses using the eye movement variables as predictors indicated that number of object presentations predicted target memory with no additional impact of other viewing measures. In contrast, distractor memory was best predicted by the viewing pattern on the distractor objects. Finally, Experiment 2 showed that target memory was influenced by number of target object presentations, not number of searches for the target. Each of these experiments demonstrates visual memory differences between target and distractor objects and may provide insight into representational differences in visual memory.

フリッカー変化時における自然情景の視覚表象

Coherence theory in scene perception (Rensink, 2002) assumes the retention of volatile object representations on which attention is not focused. On the other hand, visual memory theory in scene perception (Hollingworth & Henderson, 2002) assumes that robust object representations are retained. In this study, we hypothesized that the difference between these two theories is derived from the difference of the experimental tasks that they are based on. In order to verify this hypothesis, we examined the properties of visual representation by using a change detection and memory task in a flicker paradigm. We measured the representations when participants were instructed to search for a change in a scene, and compared them with the intentional memory representations. The visual representations were retained in visual long-term memory even in the flicker paradigm, and were as robust as the intentional memory representations. However, the results indicate that the representations are unavailable for explicitly localizing a scene change, but are available for answering the recognition test. This suggests that coherence theory and visual memory theory are compatible.

Method matters: Systematic effects of testing procedure on visual working memory sensitivity.

Visual working memory (WM) is traditionally considered a robust form of visual representation that survives changes in object motion, observer's position, and other visual transients. This article presents data that are inconsistent with the traditional view. We show that memory sensitivity is dramatically influenced by small variations in the testing procedure, supporting the idea that representations in visual WM are susceptible to interference from testing. In the study, participants were shown an array of colors to remember. After a short retention interval, memory for one of the items was tested with either a same-different task or a 2-alternative-forced-choice (2AFC) task. Memory sensitivity was much lower in the 2AFC task than in the same-different task. This difference was found regardless of encoding similarity or of whether visual WM required a fine or coarse memory resolution. The 2AFC disadvantage was reduced when participants were informed shortly before testing which item would be probed. The 2AFC disadvantage diminished in perceptual tasks and was not found in tasks probing visual long-term memory. These results support memory models that acknowledge the labile nature of visual WM and have implications for the format of visual WM and its assessment.

Study of Neurobehavioral Symptoms and Impairments in Breast Cancer Patients Receiving Adjuvant Aromatase Inhibitor Therapy.

Abstract Background: Whether treatment with aromatase inhibitors (AI) may be associated with the development of cognitive or other mental impairments is under debate. Few studies have carefully assessed AI-associated changes in cognitive function, and none have assessed differences between the three third-generation AIs – anastrozole, letrozole, and exemestane. We initiated a prospective clinical trial to compare baseline and 1-year change in neurophysiological testing in women initiating adjuvant AI.Patients and Methods: Women with a hormone receptor-positive stage 0-III breast cancer who were about to begin AI treatment were eligible for enrollment. We compared intra-individual neurophysiological testing results at baseline (Session I) and following one year of AI (Session II). Cognitive/behavioral assessment included standardized tests sensitive to 8 neuropsychological domains: General Intelligence, Attention, Perceptual-motor Performance, Working Memory, Visual Long-term Memory, Verbal Long-term Memory, Language, and Executive Functioning. Scoring was based upon age- and education-adjusted normative data. In addition, participants completed several subjective reports of cognitive, physical, and emotional functioning.Results: To date, 53 subjects enrolled in Session I, and 30 completed Session II. Analysis of the 30 women who completed both sessions revealed statistically significant differences (with the significance level set at p=0.05, test-wise), including: impairment from Session I to Session II on the PASAT Trial I (p=0.005) and improvement from Session I to Session II on the following tests: FAS Total (p<0.001); Animal Naming (p=0.025); RAVLT I-V, B, Delay, and Immediate (p<0.001 for all); RAVLT 5-1 (p=0.017); RAVLT % (p=0.022); Logical Memory I (p=0.005) and II (p<0.001); WMS-Faces I & II (p<0.001 for both); WAIS-Picture Completion (p=0.027); and WAIS-Vocabulary (p<0.001).Discussion: Only a few studies have examined the effect of AI treatment on cognitive functioning. Findings from the present study suggest that, following the administration of AI for 1 year, women as a group appear to exhibit impairments in attention (as evidenced by PASAT performance) and possibly in executive functioning. However, there was also improved performance in the areas of language, verbal long-term memory, and visual long-term memory. These preliminary results suggest a need to be sensitive to the possibility that AI treatment may have mixed effects on cognitive and related behavioral functions. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4084.

Role of Layer 6 of V2 Visual Cortex in Object-Recognition Memory

Cellular responses in the V2 secondary visual cortex to simple as well as complex visual stimuli have been well studied. However, the role of area V2 in visual memory remains unexplored. We found that layer 6 neurons of V2 are crucial for the processing of object-recognition memory (ORM). Using the protein regulator of G protein signaling-14 (RGS-14) as a tool, we found that the expression of this protein into layer 6 neurons of rat-brain area V2 promoted the conversion of a normal short-term ORM that normally lasts for 45 minutes into long-term memory detectable even after many months. Furthermore, elimination of the same-layer neurons by means of injection of a selective cytotoxin resulted in the complete loss of normal as well as protein-mediated enhanced ORM.

Category-specificity in visual object recognition

Are all categories of objects recognized in the same manner visually? Evidence from neuropsychology suggests they are not: some brain damaged patients are more impaired in recognizing natural objects than artefacts whereas others show the opposite impairment. Category-effects have also been demonstrated in neurologically intact subjects, but the findings are contradictory and there is no agreement as to why category-effects arise. This article presents a pre-semantic account of category-effects (PACE) in visual object recognition. PACE assumes two processing stages: shape configuration (the binding of shape elements into elaborate shape descriptions) and selection (among competing representations in visual long-term memory), which are held to be differentially affected by the structural similarity between objects. Drawing on evidence from clinical studies, experimental studies with neurologically intact subjects and functional imaging studies, it is argued that PACE can account for category-effects at both behavioural and neural levels in patients and neurologically intact subjects. The theory also accounts for the way in which category-effects are affected by different task parameters (the degree of perceptual differentiation called for), stimulus characteristics (whether stimuli are presented as silhouettes, full line-drawings, or fragmented forms), stimulus presentation (stimulus exposure duration and position) as well as interactions between these parameters.

Visual perception and imagery: A new molecular hypothesis

Here, we put forward a redox molecular hypothesis about the natural biophysical substrate of visual perception and visual imagery. This hypothesis is based on the redox and bioluminescent processes of neuronal cells in retinotopically organized cytochrome oxidase-rich visual areas. Our hypothesis is in line with the functional roles of reactive oxygen and nitrogen species in living cells that are not part of haphazard process, but rather a very strict mechanism used in signaling pathways. We point out that there is a direct relationship between neuronal activity and the biophoton emission process in the brain. Electrical and biochemical processes in the brain represent sensory information from the external world. During encoding or retrieval of information, electrical signals of neurons can be converted into synchronized biophoton signals by bioluminescent radical and non-radical processes. Therefore, information in the brain appears not only as an electrical (chemical) signal but also as a regulated biophoton (weak optical) signal inside neurons. During visual perception, the topological distribution of photon stimuli on the retina is represented by electrical neuronal activity in retinotopically organized visual areas. These retinotopic electrical signals in visual neurons can be converted into synchronized biophoton signals by radical and non-radical processes in retinotopically organized mitochondria-rich areas. As a result, regulated bioluminescent biophotons can create intrinsic pictures (depictive representation) in retinotopically organized cytochrome oxidase-rich visual areas during visual imagery and visual perception. The long-term visual memory is interpreted as epigenetic information regulated by free radicals and redox processes. This hypothesis does not claim to solve the secret of consciousness, but proposes that the evolution of higher levels of complexity made the intrinsic picture representation of the external visual world possible by regulated redox and bioluminescent reactions in the visual system during visual perception and visual imagery.

Detecting changes in real-world objects: The relationship between visual long-term memory and change blindness

A large body of literature has shown that observers often fail to notice significant changes in visual scenes, even when these changes happen right in front of their eyes. For instance, people often fail to notice if their conversation partner is switched to another person, or if large background objects suddenly disappear.1,2 These ‘change blindness’ studies have led to the inference that the amount of information we remember about each item in a visual scene may be quite low.1 However, in recent work we have demonstrated that long-term memory is capable of storing a massive number of visual objects with significant detail about each item.3 In the present paper we attempt to reconcile these findings by demonstrating that observers do not experience ‘change blindness’ with the real world objects used in our previous experiment if they are given sufficient time to encode each item. Our results (see also refs. 4 and 5) suggest that one of the major causes of change blindness for real-world objects is a lack of encoding time or attention to each object.