"A theory of visual information acquisition and visual memory with special application to intensity-duration trade-offs": Correction.

Reports an error in the original article by G. R. Loftus and E. Ruthruff (Journal of Experimental Psychology: Human Perception and Performance, 1994[Feb], Vol 20[1], 33–49). A corrected Figure 4 is presented. (The following abstract of this article originally appeared in record 1994-24283-001.) Describes a theory of memory for visual material in which the visual system acts as linear filter operating on a stimulus to produce a function, a(t), relating some sensory response to t (the time since stimulus onset). Stimulus information is acquired at a rate proportional to the product of the magnitude by which a(t) exceeds some threshold, and the amount of as-yet-unacquired information. The theory accounts for data from 2 digit-recall experiments in which stimulus temporal waveform was manipulated. The authors comment on the theory's account of the relation between 2 perceptual events: the phenomenological experience of the stimulus, and the memory representation that accrues from stimulus presentation. It is asserted that these 2 events, although influenced by different variables, can be viewed as resulting from 2 characteristics of the same sensory-response function. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sensory and cognitive components of visual information acquisition.

Describes a theory of visual information acquisition and visual memory. The theory has 2 major components. First, the visual system's initial sensory response to a short-duration, low-contrast stimulus is generated by a linear, low-pass temporal filter that operates on the stimulus's temporal waveform. Second, information is acquired from a stimulus through an independent-sampling process whose sampling rate at time t following stimulus onset is jointly proportional to (1) the magnitude by which the sensory response exceeds some threshold and (2) the proportion of still unacquired information. The theory was successfully tested in 5 variants of a digit recall task in which temporal waveform of the stimulus was systematically manipulated. In a final experiment, the theory simultaneously accounted for performance in detection and identification tasks. Implications for visual information processing, low-contrast detection, and binocular combination of information are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Binocular information acquisition and visual memory.

Mechanisms underlying the binocular combination of visual information were investigated within the context of a visual information acquisition theory proposed by G. R. Loftus et al (e.g., as described by T. A. Busey and G. R. Loftus, 1994). A central assumption of the theory is that of a sensory threshold, which engenders an information loss such that information processing subsequent to the threshold is assumed to occur only when the magnitude of a sensory representation triggered by the stimulus exceeds the threshold. The presumed sensory threshold may be situated prior to or subsequent to the point at which the information from the two eyes combines. The location of this threshold was investigated in 3 experiments that provided conclusions about the location of the sensory thresholds and the mechanisms of binocular combination. It is concluded that a linear summation mechanism, an independent sampling information acquisition model, and both pre- and postcombinatorial sources of information loss are required to account for the data. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Evoked potential studies of visual perception

Discusses the use of evoked potentials (EPs) to study the sensory processing of visual information. Two types of response, transient and steady-state, can provide complementary information, and in some situations the steady-state method is speedier. EPs can be treated as objective signs that visual signals have arrived at the cortex. The experimenter can then manipulate stimulus variables (as in psychophysics) and record EPs that are specific to stimulus features (e.g., spatial contrast, color, stereoscopic depth, motion, and flicker). In situations where there is a close correlation between EPs and visual perceptions, EP recording offers a means of (1) extending psychophysical studies on sensory channels to include physiological data, (2) investigating visual processing at super- and subthreshold levels, (3) testing subtle visual functions in infants with eye pathway disorders, (4) monitoring visual maturation in babies, and (5) linking single-cell studies in animals with human psychophysics. (French abstract) (169 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Two representational systems in dynamic visual identification.

How does the visual system retain and combine information about an object across time and space? This question was investigated by manipulating the spatiotemporal continuity and form continuity of 2 perceptual objects over time. In Experiment 1 the objects were viewed in central vision within a single eye fixation, in Experiment 2 they were viewed across a saccadic eye movement, and in Experiment 3 they were viewed at different spatial and retinal locations over time. In all 3 experiments some information about the object was found to be linked to its spatiotemporal continuity, and some information was found to be independent of spatiotemporal continuity. Form continuity was found to produce no effect. The results support a theory of dynamic visual identification according to which information is maintained over time by both episodic object representations and long-term memory representations, neither of which necessarily code specific sensory information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual processing and the use of redundant information in tachistoscopic recognition.

Examined the relation between information available in the stimulus and information required in report. 54 undergraduates in 3 groups reported on the basis of different attributes of 4 sets of visual stimuli varying in form of redundancy. Loss of information from conic memory was measured by means of a partial report procedure. The redundancy manipulation affected the level of accuracy and there was differential loss of stimulus information from iconic memory, depending on the stimulus attribute to be reported. There was, however, no relation between redundancy and loss of information. Results show that (a) the use of stimulus information plays an important role in accuracy, and (b) there are some basic differences in the way in which the visual system treats different categories of information. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Impairment of visual object-discrimination learning after perirhinal cortex ablation.

Eight cynomolgus monkeys learned preoperatively 20 concurrent visual discriminations between pairs of colored shapes presented on a touch screen with 24-hr intertrial intervals. Three then received bilateral perirhinal cortex ablation, and 5 remained controls. The ablated monkeys were severely impaired in reacquiring the preoperatively acquired set, whereas postoperative learning of 20 new discriminations was not significantly affected. The task was then made more difficult. First, the number of foils from which the stimulus had to be selected was increased to 2, 4, 7, and then 14. Second, larger sets of 40, 80, and 160 problems were presented. Both manipulations revealed some significant but relatively mild impairments in the monkeys with ablations. It is suggested that perirhinal cortex ablation impairs the monkey's capacity to identify individual objects, which leads to deficits in both visual-object recognition memory and discrimination learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dimensions of stimulus complexity.

Animal reaming research has increasingly used complex stimuli that approximate natural objects, events, and locations, a trend that has accompanied a resurgence of interest in the role of cognitive factors in reaming. Accounts of complex stimulus control have focused mainly on cognitive mechanisms and largely ignored the contribution of stimulus information to perception and memory for complex events. It is argued here that research on animal reaming stands to benefit from a more detailed consideration of the stimulus and that James Gibson's stimulus-centered theory of perception serves as a useful framework for analyses of complex stimuli. Several issues in the field of animal reaming and cognition are considered from the Gibsonian perspective on stimuli, including the fundamental problem of defining the effective stimulus. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dual-task interference and visual encoding.

A visual target (T?) containing either 1 or 2 letters, or a random 10-sided polygon, was presented after an auditory target (T?) at a stimulus onset asynchrony (SOA) of either 50, 150, 250, or 600 ms. Task? was a speeded pitch discrimination to the tone, and across experiments, T? was either 1 of 2 tones (2-alternative discrimination [2AD]) or 1 of 4 tones (4-alternative discrimination [4AD]). Memory for the visual information decreased as SOA was reduced when a mask was used, but not when there was no mask. The effects of SOA were larger for the 4AD Task? than the 2AD Task?. The results demonstrate cross-modal, dual-task interference on visual encoding and suggest central interference with the short-term consolidation of visual information in short-term memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An efferent component in the visual perception of direction and extent.

Outlines the history of motor theories of visual perception and presents a new theory linking information extraction patterns, specifically adapted for the guidance of eye movements, to the visual perception of direction and extent. Following a brief discussion of comparative and physiological considerations, a research strategy to test for efferent involvement in human visual perception is presented. In 7 demonstration experiments, predictions from efferent considerations are used to create a new set of illusions of direction and extent and to demonstrate new predictable variations in the magnitude of some classical illusion figures. Another demonstration illustrates that systematic changes in visual perception occur as a function of changes in motoric demands, even in the absence of any configurational changes in the stimulus. The relationship between attenuation and efferent readiness and their interaction in the formation of the conscious visual percept are illustrated. (64 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Relationship between the characteristics of visual short-term memory in monkeys and the spatial properties of images

Experiments were performed on Rhesus macaques to study the relationship between delayed visual differentiation processes and stimulus properties. These investigations showed that the processes of short-term storage of visual information in monkeys has significant features associated with differences in stimulus properties. These consisted of different durations of storage and motor response times. Because of these differences, stimuli (15 pairs) could be grouped into compact clusters on the bases of similarity between their delayed differentiation characteristics. These experiments characterized the processes of short-term information storage during the differentiation of stimuli differing in terms of spatial relationships between elements, as compared with stimuli differing in terms of other attributes (shape, color, etc.); spatial information was stored for shorter periods of time and motor response times were longer. It is suggested that visual short-term memory involves a set of mechanisms operating on attributes of different types and which, along with signs and working programs associated with the visual system, stores spatial discriminatory signs, in which the major role is played by visual-vestibular interactions.     

Attention and modality specific interference as determinants of short-term verbal and visual retention.

Conducted 2 experiments with a total of 210 undergraduates to investigate short-term retention of verbal and visual information as a function of interpolated activities, varying along the dimensions of attention and modality specific interference. Results show that retention losses due to competing attention demands were comparable in verbal and visual coding conditions, regardless of the modality of the interpolated activity. In addition, retention losses were larger when the same modality was involved in processing the memory and interpolated tasks. Results demonstrate a clear separation of short-term losses due to (a) attention diversion, and (b) modality specific interference, with attention diversion accounting for a larger part of total retention losses. It is proposed that the maintenance of information for short intervals relies on the availability of central attentional processes, with modality specific coding processes determining the most appropriate coding mode for a given stimulus situation. (French summary) (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Parrel processing in visual short-term memory.

Visual short-term memory for the contrast and spatial frequency of sinusoidal gratings was measured in a delayed discrimination task in which the 2 stimuli to be compared were separated in time by 1-10 s interstimulus intervals (ISIs). Delayed discrimination thresholds for spatial frequency and contrast were compared, both when the 2 types of thresholds were measured in separate blocks of trials and when the 2 types of measures were randomly intermixed in an uncertainty paradigm, which required participants to process information about both dimensions on each trial. In both cases, accuracy of memory for spatial frequency was independent of ISI, but memory for contrast decreased as ISI increased. Performance was lower in the uncertainty case, but only by an amount predicted by statistical decision theory for independent sources. The results are consistent with a model assuming a set of parallel special-purpose visual discrimination and short-term memory mechanisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of visual, haptic, and manipulatory experiences on infants' visual recognition memory of objects.

To determine the effects of visual, haptic, and manipulatory experiences on visual recognition of objects' shapes, 108 6-, 9-, and 12-mo-old infants were randomly assigned to 1 of 3 stimulus familiarization conditions in which they either only looked at an object (visual), looked at and manipulated an object (visual-haptic), or looked at an object encased in a transparent box that the infant manipulated (visual-manipulatory). Visual recognition memory was assessed by the paired-comparison technique in which memory is indexed by infants' differential preferences for novel and familiar stimuli. The major findings were that (a) 12-mo-olds showed evidence of memory in all conditions, (b) younger Ss showed evidence of memory only in the visual condition, and (c) at all ages Ss' preference for novel relative to familiar stimuli was significantly greater in the visual condition than in the visual-haptic and visual-manipulatory conditions, with the latter conditions not differing significantly. It is argued that the manipulatory activity per se depressed Ss' differential preferences in the visual-haptic and visual-manipulatory conditions. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rats spontaneously discriminate purely visual, two-dimensional stimuli in tests of recognition memory and perceptual oddity.

Animal models have been central to advances made in understanding the neural basis of human cognition, but maximizing the use of animal models requires tasks that match those used to assess human subjects. Tasks used in humans frequently use visual 2-dimensional stimuli, assess 1-trial learning, and require little pretraining. This article describes novel versions of 2 tasks for the rat, spontaneous object recognition and spontaneous oddity preference, both of which use purely visual, 2-dimensional picture-card stimuli, test 1-trial learning, and require no pretraining. Rats showed robust memory for a variety of picture-card stimuli, demonstrating almost no loss of memory for some of the stimulus types even after a 2-hr delay period. Rats were able to show spontaneous oddity preference for all 3 visual stimulus types tested (photos, shapes, and patterns), as well as for 3-dimensional objects. These 2 tasks are quick to administer, involve no fearful learning associations, and require a simple apparatus. They may be particularly useful for high-throughput pharmacological or genetic screening using rodent models. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Retention and disruption of motion information in visual short-term memory.

Velocity discrimination thresholds for drifting luminance gratings were measured as a function of the time interval between test and reference gratings, using a 2-interval, forced-choice procedure. Discrimination thresholds, expressed as Weber fractions (ΔV/V), were independent of interstimulus interval (ISIs) ranging from 1 to 30 sec, demonstrating perfect short-term retention of velocity information. When a 3rd grating was briefly presented halfway through a 10-sec ISI, memory masking was observed. Discrimination thresholds in memory masking were unaffected by maskers of the same velocity but increased by 100% when test and masker velocity differed by a factor of 2. The results are interpreted with reference to a model where the short-term memory for simple stimulus attributes is assumed to be organized in terms of arrays of memory stores linked in a lateral inhibitory network. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Michael Turvey.

Announces Michael Turvey as a recipient of the 1974 Early Career Award, and presents his biography and list of scientific publications. His most important research contribution to date is his information-processing analysis of peripheral and central visual mechanisms. Turvey elucidated the processes involved in forward and backward masking by cleanly designed experiments utilizing noise and pattern masks presented either monoptically or dichoptically. Further, in his 1973 Psychological Review paper he integrated his results with a large body of literature on both visual theory and psychological experiments in terms of a model for the concurrent-contingent relationships between peripheral and central processes in the sequence of events leading from the onset of a visual display to recognition of a stimulus. In addition, he has been responsible for an extensive series of studies analyzing the function of release from proactive inhibition in short-term memory. He and his associates have contributed methods for studying primary or iconic memory, including an auditory analogue of Sperling's partial report procedure. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Temporal gating of neural signals during performance of a visual discrimination task

The flow of neural signals within the cerebral cortex must be subject to multiple controls as behaviour unfolds in time. In a visual discrimination task that includes a delay period, the transmission of sensory signals to circuitry that mediates memory, decision-making and motor-planning must be governed closely by 'filtering' or 'gating' mechanisms so that extraneous events occurring before, during or after presentation of the critical visual stimulus have little or no effect on the subject's behavioural responses. Here we study one such mechanism physiologically by applying electrical microstimulation to columns of directionally selective neurons in the middle temporal visual area at varying times during single trials of a direction-discrimination task. The behavioural effects of microstimulation varied strikingly according to the timing of delivery within the trial, indicating that signals produced by microstimulation may be subject to active 'gating'. Our results show several important features of this gating process: first, signal flow is modulated upwards on onset of the visual stimulus and downwards, typically with a slower time course, after stimulus offset; second, gating efficacy can be modified by behavioural training; and third, gating is implemented primarily downstream of the middle temporal visual area.     

Binding in short-term visual memory.

The integration of complex information in working memory, and its effect on capacity, shape the limits of conscious cognition. The literature conflicts on whether short-term visual memory represents information as integrated objects. A change-detection paradigm using objects defined by color with location or shape was used to investigate binding in short-term visual memory. Results showed that features from the same dimension compete for capacity, whereas features from different dimensions can be stored in parallel. Binding between these features can occur, but focused attention is required to create and maintain the binding over time, and this integrated format is vulnerable to interference. In the proposed model, working memory capacity is limited both by the independent capacity of simple feature stores and by demands on attention networks that integrate this distributed information into complex but unified thought objects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)