Stroke width, illumination level, and figure-ground contrast in numeral visibility.

Two levels each of three numeral visibility variables (stroke width to height ratios of 1:4 and 1:16; illumination level of 0.5 foot-candles and 500 foot-candles; mode of figure-ground contrast-black numbers on white background and the reverse) were studied in a 2 X 2 X 2 analysis of variance, using 40 Ss who provided 5 replications of each possible condition. Of the main effects, only illumination level showed a significant effect on visibility. Stroke width interacted significantly with both illumination level and mode of figure-ground contrast, but the latter two variables did not interact. The interaction of all three variables was also significant. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The preattentive emperor has no clothes: A dynamic redressing.

Preattentive models of early vision have not been supported by the evidence. Instead, an input filtering system, which is dynamically reconfigured so as to optimize performance on the task at hand, is proposed. As a case in point, the authors examined Sagi and Julesz's (1985a) claim that detection tasks are processed preattentively and efficiently (shallow search slopes), whereas discrimination tasks require focal attention and yield inefficient steep slopes. In 5 visual search experiments, efficiency was found to depend not on the nature of the task but on whether the task is single or dual. The second component of a dual task, whether detection or discrimination, is performed inefficiently if it does not fit the configuration of the input system, which had been set optimally for the first component. But, even the second component is processed efficiently if there is enough time to reconfigure the system after processing the first component. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Location serves as a conditional cue when harp seals (Pagophilus groenlandicus) solve object discrimination reversal problems.

We examined the capacity of harp seals (Pagophilus groenlandicus) to use spatial context (i.e., their tank) as a conditional cue to solve a two-choice visual discrimination reversal task. Seals were trained to touch one of two 3D objects. Two of four seals experienced a context shift that coincided with each of five reversals in the reward value of the two stimuli (i.e., a reversal of S+ and S-); these seals solved the six discriminations in significantly fewer trials than did seals that did not experience a context shift with the contingency reversal. Thus, harp seals use contextual cues when encoding information. The findings are discussed in terms of harp seals' adaptations to the pack-ice environment, the constraints of the learning tasks, and the nature of the subjects that were raised in captivity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attentional bias in drug dependence: Vigilance for cigarette-related cues in smokers.

Two experiments investigated attentional biases for smoking-related cues in smokers and nonsmokers, using the visual probe task. In Experiment 1, when pictures were displayed for 500 ms, smokers who had made repeated quit attempts showed an attentional bias for smoking-related scenes. Experiment 2 replicated this finding and revealed that when pictures were presented for 2,000 ms, the smoker group as a whole showed vigilance for smoking-related cues, but nonsmokers did not. The findings from the 500-ms exposure condition suggest that initial orienting of attention to smoking cues was associated with repeated unsuccessful attempts at abstinence in smokers. Results are discussed with reference to incentive-sensitization theories of addiction and to component processes of selective attention, such as initial orienting versus maintenance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of the dorsomedial striatum in behavioral flexibility for response and visual cue discrimination learning.

These experiments examined the effects of dorsomedial striatal inactivation on the acquisition of a response and visual cue discrimination task, as well as a shift from a response to a visual cue discrimination, and vice versa. In Experiment 1, rats were tested on the response discrimination task followed by the visual cue discrimination task. In Experiment 2, the testing order was reversed. Infusions of 2% tetracaine did not impair acquisition of the response or visual cue discrimination but impaired performance when shifting from a response to a visual cue discrimination, and vice versa. Analysis of the errors revealed that the deficit was not due to perseveration of the previously learned strategy, but to an inability to maintain the new strategy. These results contrast with findings indicating that prelimbic inactivation impairs behavioral flexibility due to perseveration of a previously learned strategy. Thus, specific circuits in the prefrontal cortex and striatum may interact to enable behavioral flexibility, but each region may contribute to distinct processes that facilitate strategy switching. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stimulus dynamics and temporal discrimination: Implications for pacemakers.

The purpose of the present study was to observe the functional relationship between stimulus dynamics and stimulus duration judgments in humans. Stimulus duration was defined as the length of time that a spinning sphere appeared on a computer screen. Stimulus dynamics were defined by how quickly the sphere rotated on its y-axis. Using a logarithmic scale, a psychophysical bisection task was used to divide stimulus durations into two categories, short and long. Across three experiments, participants’ duration judgments were longer the faster the sphere was rotated. This effect was observed over both a long and short temporal scale and over a wide range of stimulus dynamics despite the fact that the reinforcement contingencies penalized participants for this effect. The results are discussed in terms of perceived change as the possible basis of temporal duration estimation. This hypothesis was investigated through applications of the leading quantitative models of temporal discrimination to the present data. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"The role of reinforcement symmetry and stimulus modality in successive delayed matching to sample in the rat": Correction.

Reports an error in "The role of reinforcement symmetry and stimulus modality in successive delayed matching to sample in the rat" by J. S. Cohen, M. Escott and P. Ricciardi (Canadian Journal of Psychology Revue Canadienne de Psychologie, 1984[Mar], Vol 38[1], 63-79). The last six words of the legend for Figure 1 should read "in the replication of Experiment 1." (The following abstract of the original article appeared in record 1985-05863-001.) 20 male Wister albino rats were trained and tested in asymmetrically and symmetrically reinforced successive delayed matching to sample (DMTS) tasks. The only difference between these discrimination problems was that correct omission of a leverpress to the test stimulus (S?), differing from the sample stimulus (S?), was reinforced in the symmetrically reinforced DMTS. Response biases during tests for retention of S? were reduced in the symmetrically reinforced DMTS. Greater losses in retention occurred to the visual than to the auditory S?. For the auditory S?, reduced response biases in the symmetrically reinforced DMTS led to reduced losses in S? retention scores over increased retention intervals. Methodological and theoretical implications are discussed in terms of the theory of signal detection. (French abstract) (28 ref). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An investigation of clinical judgment: A study in method.

To investigate the accuracy of judgment in the use of cues in a perceptual discrimination task, 2 sets of cards were constructed: 1 where the relevant cue was color; the other, size. Ss were required to identify the cue dimension. Some Ss were given prior training in cue-identification, some not. In a 2nd reported experiment a spatial task was constructed. Ss had to make judgments and predict how other Ss would perform on a task after receiving certain information about them. Both experiments intended to explore the nature of the judgmental process as it may be understood from a laboratory experiment, and in both, accuracy of judgment was improved when the judge could use more than 1 cue. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An immediate-shock freezing deficit with discrete cues: A possible role for unconditioned stimulus processing mechanisms.

Five experiments with C57BL/6 mice (Mus musculus) investigated whether failures in shock processing might contribute to deficits in freezing that occur after an animal receives a shock immediately on exposure to a conditioning context. Experiment 1 found that more contextual freezing resulted from delayed shocks than from immediate shocks across 4 shock intensities. Experiment 2 extended the immediate-shock freezing deficit to discrete stimuli. Experiment 3 found that preexposure to the to-be-conditioned cue did not facilitate immediate cued conditioning. Experiment 4 found that context preexposure enhanced context-evoked fear after an immediate shock. Experiment 5 found that context preexposure also enhanced immediate cued conditioning. These findings are problematic for current theories of the immediate-shock freezing deficit that focus exclusively on processing of the conditioned stimulus, and they suggest that failures in shock processing may contribute to the deficit. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Directly perceiving Gibson: A further reply to Gyr.

In his 1972 critique of direct theories of perception, J. W. Gyr argued from the view that Gibson believes (a) that stimulus structure can determine perception and (b) that perceiving as a consequence of voluntary activity is virtually the same as perception that is not a consequence of voluntary activity. Since neither of these assumptions is found in Gibson's approach, Gyr's criticisms do not seem to apply. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

When something old becomes something new: Spatiotemporal object continuity and attentional capture.

This article examines the possibility that the visual system treats dynamic cues as instances of new perceptual objects under some circumstances. Using the contingent capture paradigm (C. L. Folk, R. W. Remington, & J. C. Johnston, 1992), the author compared luminance change cues of different magnitude for their ability to capture attention when participants were set for new objects. Whereas small luminance changes failed to produce attentional capture, large luminance changes indeed captured attention, suggesting that they were treated as compatible with the participants' attentional set for new objects. It is argued that sufficiently large luminance transients led to a disruption of spatiotemporal object continuity and precipitated the emergence of a new perceptual object. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Discrimination of Multidimensional Visual Stimuli by Mice: Intra- and Extradimensional Shifts.

A visual discrimination protocol similar to that used with monkeys was adapted to measure attentional set-shifting in mice. An automated touchscreen procedure with compound visual stimuli was used to train mice to attend to 1 of 2 stimulus dimensions (lines or shapes). On a 2nd problem with new stimuli, the mice were required to attend to the same dimension (intradimensional [ID] shift) or switch to the previously irrelevant dimension (extradimensional [ED] shift). Mice readily learned the initial compound discrimination and following shift problem, but there was no ID-ED difference. The fact that mice can be tested with stimuli and task sequences similar to those used with primates suggests that this method can be used to directly compare higher cognitive functions in diverse species. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Olfactory and/or visual cues for spatial navigation through ontogeny: Olfactory cues enable the use of visual cues.

This study analyzed the spatial memory capacities of rats in darkness with visual and/or olfactory cues through ontogeny. Tests were conducted with the homing board, where rats had to find the correct escape hole. Four age groups (24 days, 48 days, 3-6 months, and 12 months) were trained in 3 conditions: (a) 3 identical light cues; (b) 5 different olfactory cues; and (c) both types of cues, followed by removal of the olfactory cues. Results indicate that immature rats first take into account olfactory information but are unable to orient with only the help of discrete visual cues. Olfaction enables the use of visual information by 48-day-old rats. Visual information predominantly supports spatial cognition in adult and 12-month-old rats. Results point out cooperation between vision and olfaction for place navigation during ontogeny in rats. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Discrimination of structure: I. Implications for connectionist theories of discrimination learning.

In each of 4 experiments animals were given a structural discrimination task that involved visual patterns composed of identical features, but the spatial relations among the features were different for reinforced and nonreinforced trials. In Experiment 1 the stimuli were pairs of colored circles, and pigeons were required to discriminate between patterns that were the mirror image of each other. A related task was given to rats in Experiment 2. Subjects solved these discriminations. For Experiment 3, some pigeons were given a discrimination similar to that used in Experiment 1, which they solved, whereas others received a comparable task but with 3 colored circles present on every trial, which they failed to solve. The findings from Experiment 3 were replicated in Experiment 4 using different patterns. The results are difficult to explain by certain connectionist theories of discrimination learning, unless they are modified to take account of the way in which compound stimuli are structured. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Enhanced release from proactive interference in nonamnesic alcoholic individuals: Implications for impaired associative binding.

Proactive interference (PI) occurs when previously learned information reduces the ability to acquire new, related information. Given that PI is modulated by the cholinergic system in rats (E. De Rosa & M. E. Hasselmo, 2000) and that chronic alcohol dependence disrupts cholinergic function in rats and humans, associative properties of PI in patients with alcoholism were examined. It was hypothesized that normal PI contingencies would be disrupted in alcoholic participants. When tested with a paired-associate simultaneous discrimination paradigm, analogous to that used in the rat model, alcoholic participants showed significantly less PI than controls yet performed comparably on a control response reversal task. The absence of PI in alcoholic participants may reflect impaired configural binding of paired-associate stimuli while sparing the elemental ability to process each stimulus component. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A new psychophysical method: Method of transposition or equal-appearing relations.

"In many experiments dealing with perceptual phenomena, investigators try to find a stimulus which appears equal to a standard stimulus. It often happens, however, that the procedure involved in finding the equivalent stimulus alters the stimulus pattern so that the measurement is not made on the original stimulus pattern. To avoid this difficulty, a new psychophysical method, which is named the method of transposition or the method of equal-appearing relations, was proposed. The major advantage of this method over the traditional ones is that it leaves the original stimulus pattern intact." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Representational conceptions in two- and three-dimensional media: A developmental perspective.

Some of the empirical implications of Rudolf Arnheim's concept of representation as a mental activity that goes beyond the perception and imitation of objects and events and transforms them with the means available in a chosen medium are explored in the study of two- and three-dimensional media. Systematic comparisons of children's drawings and their models in clay, and comparisons of diverse objects within the three-dimensional medium reveal significant differences in the form their representations take. The findings highlight the role of the medium in the art form children invent and do not support the notion that a single template underlies their diverse attempts at representation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Discrimination of computer-graphic stimuli by mice: A method for the behavioral characterization of transgenic and gene-knockout models.

An automated method is described for the behavioral testing of mice in an apparatus that allows computer-graphic stimulus material to be presented. Mice responded to these stimuli by making a nose-poke toward a computer monitor that was equipped with a touchscreen attachment for detecting responses. It was found that C57BLJ/6 mice were able to solve single-pair visual discriminations as well as 3-pair concurrent visual discriminations. The finding that mice are capable of complex visual discriminations introduces the possibility of testing mice on nonspatial tasks that are similar to those used with rats, monkeys, and humans. Furthermore, the method seems particularly well suited to the comprehensive behavioral assessment of transgenic and gene-knockout models. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A comparison of discrimination and reversal learning for olfactory and visual stimuli in aged rats.

The present study investigated age-related differences in discrimination and reversal learning for olfactory and visual stimuli in 6-month and 24-month-old rats. Rats were trained to discriminate between two pseudo-randomly selected odors or objects. Once each animal reached a criterion on discrimination trials, the reward contingencies were reversed. Young and aged rats acquired the olfactory and visual discrimination tasks at similar rates. However, on reversal trials, aged rats required significantly more trials to reach the learning criterion on both the olfactory and visual reversal tasks than young rats. The deficit in reversal learning was comparable for odors and objects. Furthermore, the results showed that rats acquired the olfactory task more readily than the visual task. The present study represents the first examination of age-related differences in reversal learning using the same paradigm for odors and objects to facilitate cross-modal comparisons. The results may have important implications for the selection of memory paradigms for future research studies on aging. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hemispheric asymmetries for global and local visual perception: Effects of stimulus and task factors.

Although neurological and physiological studies indicate a right hemisphere superiority in global processing and a left hemisphere superiority in local processing of Navon-type hierarchical letters (D. Navon, 1977), most investigations of lateralized perception in healthy participants report neither asymmetry. In 6 experiments the authors examined the influence of attentional demands, stimulus properties, and mode of response on perceptual asymmetries for global and local perception. Consistent with their theoretical predictions, asymmetries were more robust on divided- than focused-attention tasks and in response to stimuli in which local and global levels were equally salient compared with those with greater global than local saliency. Contrary to their prediction, perceptual asymmetries were not influenced by the complexity of the motor response. (PsycINFO Database Record (c) 2010 APA, all rights reserved)