Simultaneous and sequential conditioned inhibition in autoshaping

Two experiments examined sequential and simultaneous conditioned inhibition in an autoshaping preparation. In Experiment 1, a 5-sec coloured keylight (A) was reinforced when presented alone. However, reinforcement was withheld from trials on which A was preceded by one grid pattern or presented simultaneously with another pattern. A third (control) pattern was presented separately without reinforcement. Inhibition developed most strongly to the grid pattern presented simultaneously with A. However, a transfer test with another excitatory coloured keylight found both inhibitors to be equally strong whether they were tested in simultaneous or in sequential compound. Experiment 2 compared grid patterns that consistently had sequential or simultaneous relations to the excitor with one that was sometimes presented in sequential and sometimes in simultaneous compound. The mixed treatment pattern showed levels of inhibition like the simultaneous or sequential pattern, depending on the temporal relation it bore to A on a particular trial. These results suggest that sequential and simultaneous relations between inhibitors and excitors yield similar amounts of inhibition. However, that inhibition is better exhibited when tested in simultaneous compound with the excitor.     

Frequency, phase, and colour coding in apparent motion.

We present some results which indicate that the known spatiotemporal limits for apparent motion are consistent with the motion being sinusoidal or a result of filtering. Given this we investigated how two such motions interact as a function of their relative temporal phase differences. This was accomplished by inducing two independent motions from complementary coloured event pairs. Results indicated critical phase limits for perceiving the two motions (red and green) which were consistent with the frequency specificity of the effect. The results are discussed within the framework of a filtering process for the perception of apparent motion.     

Recognising the forest, but not the trees: an effect of colour on scene perception and recognition

Colour has been shown to facilitate the recognition of scene images, but only when these images contain natural scenes, for which colour is 'diagnostic'. Here we investigate whether colour can also facilitate memory for scene images, and whether this would hold for natural scenes in particular. In the first experiment participants first studied a set of colour and greyscale natural and man-made scene images. Next, the same images were presented, randomly mixed with a different set. Participants were asked to indicate whether they had seen the images during the study phase. Surprisingly, performance was better for greyscale than for coloured images, and this difference is due to the higher false alarm rate for both natural and man-made coloured scenes. We hypothesized that this increase in false alarm rate was due to a shift from scrutinizing details of the image to recognition of the gist of the (coloured) image. A second experiment, utilizing images without a nameable gist, confirmed this hypothesis as participants now performed equally on greyscale and coloured images. In the final experiment we specifically targeted the more detail-based perception and recognition for greyscale images versus the more gist-based perception and recognition for coloured images with a change detection paradigm. The results show that changes to images are detected faster when image-pairs were presented in greyscale than in colour. This counterintuitive result held for both natural and man-made scenes (but not for scenes without nameable gist) and thus corroborates the shift from more detailed processing of images in greyscale to more gist-based processing of coloured images.     

Concave and convex phases in ambiguous figures showing colour shifts. Mach's figure and the AMBEGUJAS phenomenon

Two ambiguous figures (Mach's book-figure and the AMBEGUJAS phenomenon) have been studied. They show colour shifts synchronised with the shifts of their alternative phases. The perceived concave phase appeared to have chromatic surface colour, but the perceived convex phase can appear to be in coloured illumination and shadow (film colour). The two perceived reversible shapes of the Mach figure (the book and the tent) and the three perceived alternative shapes of the Mondrians used in the AMBEGUJAS phenomenon (a roof, a ceiling, and a tile) all can appear to have chromatic surface colours in their concave phases but appear to have coloured illumination and shadow in their convex phases.     

Diagnostic colours contribute to the early stages of scene categorization: Behavioural and neurophysiological evidence

We examined the effects of colour cues on the express categorization of natural scenes. Using a go/no-go paradigm sensitive to fast recognition processes, we measured early event-related potential (ERP) correlates of scene categorization to elucidate the processing stage at which colour contributes to scene recognition. Observers were presented with scenes belonging to four colour-diagnostic categories (desert, forest, canyon and coastline). Scenes were presented in one of three forms: Diagnostically coloured, nondiagnostically coloured, or greyscale images. In a verification task, observers were instructed to respond whenever the presented stimulus matched a previously presented category name. Reaction times and accuracy were optimal when the stimuli were presented as their original diagnostically coloured version, followed by their greyscale version, and lastly by their nondiagostically coloured version. These effects were mirrored in the early (i.e., 150 ms following stimulus onset) ERP frontal correlates. Their onset was delayed for greyscale scenes compared to diagnostically coloured scenes, and for nondiagnostically coloured scenes compared to the other two conditions. Frontal ERP amplitudes also decreased for greyscale and nondiagnostically coloured scenes. Together, the results suggest that diagnostic colours are part of the scene gist responsible for express scene categorization.     

Intracranial EEG power spectra and phase synchrony during consciousness and unconsciousness

Power density spectra and phase synchrony measurements were taken from intracranial electrode grids implanted in epileptic subjects. Comparisons were made between data from the waking state and from the period of unconsciousness immediately following a generalised tonic–clonic seizure. Power spectra in the waking state resembled coloured noise. Power spectra in the unconscious state resembled coloured noise from 1 to about 5 Hz, but at higher frequencies changed in two out of three subjects to resemble white noise. This boosted unconscious gamma power to a higher level than conscious gamma power. For both gamma and beta passbands, synchrony measurements showed more widespread phase synchrony in the unconscious than the conscious state. We conclude that neither gamma activity per se nor phase synchrony per se are neural correlates of consciousness.     

The role of colour in implicit and explicit memory performance

We present two experiments that examine the effects of colour transformation between study and test (from black and white to colour and vice versa, or from incorrectly coloured to correctly coloured and vice versa) on implicit and explicit measures of memory for diagnostically coloured natural objects (e.g., yellow banana). For naming and coloured-object decision (i.e., deciding whether an object is correctly coloured), there were shorter response times to correctly coloured-objects than to black-and-white and incorrectly coloured-objects. Repetition priming was equivalent for the different stimulus types. Colour transformation did not influence priming of picture naming, but for coloured-object decision priming was evident only for objects remaining the same from study to test. This was the case for both naming and coloured-object decision as study tasks. When participants were asked to consciously recognize objects that they had named or made coloured-object decisions to previously, whilst ignoring their colour, colour transformation reduced recognition efficiency. We discuss these results in terms of the flexibility of object representations that mediate priming and recognition.     

An Anatomy of Political Beliefs: A Study of Their Centrality, Confidence, Contents, and Epistemic Authority

The present study is a simultaneous investigation of the contents of political beliefs and their characteristics among Israeli students. In addition, it examines their perceived use of information sources. The results indicate that political beliefs regarding the Israeli-Arab conflicts are organized systematically around the dove/hawk dimension. Also, a positive relationship was found between centrality of beliefs and confidence in them; between well-defined political identification and centrality and confidence; and between agreement with the beliefs and confidence. Finally, the results show that the perceived use of information sources is related to political identification. The performed investigation demonstrates the importance of combining the study of the contents of beliefs with that of their characteristics, since the latter have important implications for understanding individuals' cognitive, affective, and behavioral reactions.     

A context-specific latent inhibition effect in a human conditioned suppression task

Three studies used a computer video game preparation to demonstrate latent inhibition in adult humans. In all studies participants fired torpedoes at a target spaceship by clicking the mouse. Conditioned stimuli (CSs) were presented in the form of coloured “sensors” at the bottom of the screen. Conditioning was conducted by pairing a sensor with an attack from the target spaceship. Participants learned to suppress their rate of mouse clicking in preparation for an attack. In Experiment 1 a total of 10 preexposures to the sensor CS, prior to conditioning, retarded acquisition of suppression. In Experiment 2 the effect of preexposure was shown to be context specific. Experiment 3 showed little generalization of the preexposure effect from one sensor CS to another. Experiment 3 also showed that preexposure did not make the sensor CS inhibitory. Comparisons with conditioned suppression procedures with animals and negative-priming procedures are briefly discussed.     

The effects of categorical similarity and feature-space proximity on visual working memory processing

Two patterns of data predict that similarity has a positive effect and a negative effect on visual working memory (VWM) processing. We assume that these two empirical outcomes do not distinguish categorical similarity from feature-space proximity, resulting in this divergence. To investigate how categorical similarity and feature-space proximity modulate VWM, we tested memory for an array of pictures drawn from either mixed categories or a single category in which feature-space proximity varied along a morph continuum in a change-detection task. We found that memory under the mixed-category condition was better than that under the single-category condition, whereas memory under high feature-space proximity was superior to that under low feature-space proximity. These patterns were unaffected by manipulations of stimulus type (faces or scenes), encoding duration (limited or self-paced), and presentation format (simultaneous or sequential). These results are consistent with our hypotheses that categorical similarity inhibits VWM, whereas feature-space proximity facilitates VWM. We also found that memory for items with low feature-space proximity benefited more from mixed-category encoding than that for items with high feature-space proximity. Memory for faces benefited more from mixed-category encoding than scenes, whereas memory for scenes benefited more from feature-space proximity than faces. These results suggest that centre-surround inhibition organization might underlie similarity effects in VWM. Centre-surround inhibition organization for complex real-world objects could have both categorical level and feature-space level. The feature-space level might differ by category.     

Edges,colour and awareness in blindsight

It remains unclear what is being processed in blindsight in response to faces, colours, shapes, and patterns. This was investigated in two hemianopes with chromatic and achromatic stimuli with sharp or shallow luminance or chromatic contrast boundaries or temporal onsets. Performance was excellent only when stimuli had sharp spatial boundaries. When discrimination between isoluminant coloured Gaussians was good it declined to chance levels if stimulus onset was slow. The ability to discriminate between instantaneously presented colours in the hemianopic field depended on their luminance, indicating that wavelength discrimination totally independent of other stimulus qualities is absent. When presented with narrow-band colours the hemianopes detected a stimulus maximally effective for S-cones but invisible to M- and L-cones, indicating that blindsight is mediated not just by the mid-brain, which receives no S-cone input, or that the rods contribute to blindsight. The results show that only simple stimulus features are processed in blindsight.     

A context-specific latent inhibition effect in a human conditioned suppression task

Three studies used a computer video game preparation to demonstrate latent inhibition in adult humans. In all studies participants fired torpedoes at a target spaceship by clicking the mouse. Conditioned stimuli (CSs) were presented in the form of coloured “sensors” at the bottom of the screen. Conditioning was conducted by pairing a sensor with an attack from the target spaceship. Participants learned to suppress their rate of mouse clicking in preparation for an attack. In Experiment 1 a total of 10 preexposures to the sensor CS, prior to conditioning, retarded acquisition of suppression. In Experiment 2 the effect of preexposure was shown to be context specific. Experiment 3 showed little generalization of the preexposure effect from one sensor CS to another. Experiment 3 also showed that preexposure did not make the sensor CS inhibitory. Comparisons with conditioned suppression procedures with animals and negative-priming procedures are briefly discussed.     

跨视听通道主动遗忘的期待加工与抑制控制过程：来自ERPs的证据

基于视觉通道的研究表明,人们可以通过主动抑制记忆提取而实现遗忘。但目前对跨通道的主动遗忘尚缺乏探讨。本研究以声音为记忆线索,以文字为目标记忆,采用“想/不想”范式,探究主动遗忘在跨视听通道条件下的可行性。结果发现,“不想”条件下目标记忆的回忆率低于基线条件,主动遗忘发生。此外,我们通过分离任务指令和记忆线索的呈现时间,在中央区域的ERP中发现了记忆抑制的期待效应;并在额叶观察到“不想”条件下晚期正成分的增强,反映了持续的抑制控制过程。本研究不但验证了跨视听通道主动遗忘的可能性,而且第一次从ERPs角度分离了跨通道遗忘相关的期待加工和抑制控制过程。     

To the letter: Early readers trust print‐based over oral instructions to guide their actions

Children have many opportunities to learn from others through oral and written sources. Recent evidence suggests that early readers place more trust in written over oral testimony when learning names for unfamiliar objects. Across three studies, we examined whether the authority of print extends beyond mere naming to guide children's actions in the physical world. In Study 1, 3‐ to 6‐year‐olds received conflicting oral and print‐based advice from two puppets about how to operate a novel apparatus. Whereas pre‐readers were indiscriminate in their trust, early readers preferred to follow the print‐based advice. In Study 2, we replicated this finding, controlling for the amount of corroborating evidence presented by both sources, and the location of the print. In Study 3, we explored whether readers' preference for print‐based information was due to a global preference for external representations, or a more specific preference for text. Children were presented with conflicting instructions based on text versus a coloured circle. Whereas pre‐readers preferred to follow the colour circle, readers preferred to follow the text. Together, the results suggest that when children learn to read, they rapidly come to regard the written word as a particularly authoritative source of information about how to act in the world.     

Associative blocking of the mccollough effect

After exposure to two simultaneously presented achromatic grids (A and B) on a coloured field, subjects reported colour aftereffects on each of the separately presented grids. These aftereffects were shown to be examples of the McCollough effect, since they were contingent upon the subjects having experienced the grid in combination with the coloured field. Exposure to the coloured field in advance of combining the colour field with the grids attenuated the strengths of the aftereffects on the A and B grids. Moreover, exposure to the A grid on the coloured field in advance of combining the B grid with the A grid on the coloured field abolished the aftereffect on the B grid. The failure of the B grid to arouse the aftereffect was due to the presence of the already trained A grid, since exposure to the A grid on the coloured field followed by exposure to the B grid on that field yielded the aftereffect on the B grid. The conditions under which the McCollough effect was attenuated are those under which learning fails to occur in Pavlovian conditioning procedures. The results, therefore, supported the view that the pairing between the grids and the colour resulted in a learned association between the grids and some aspect of the response by the visual system to the colour.     

Does Children's Colour Use Reflect the Emotional Content of their Drawings?

When children draw in clinical contexts, clinicians sometimes rely on children's colour use to make inferences about their emotional reaction to the subject of the drawing. Here, we examined whether children use colour to portray emotion in their drawings. In Experiment 1, children indicated their colour preferences and then coloured in outlines of figures characterized as nasty or nice. Children also drew complex, multi‐coloured pictures about their own happy or sad experiences. In Experiment 2, hospitalized children drew about being worried or scared in hospital and about their positive experiences. In both experiments, we examined the relation between children's colour use and their colour preferences. Three‐ to 10‐year‐old children used more preferred colours to colour in the nice outline. Although they were more likely to use non‐preferred colours to colour in the nasty outline, they tended to used a mix of preferred and non‐preferred colours. When both normal and hospitalized children produced drawings about positive and negative events, there was no relation between children's colour choices and their colour preferences; children primarily used preferred colours. These data suggest that clinicians should exercise extreme caution when interpreting the meaning of colour in children's drawings. Copyright © 2011 John Wiley & Sons, Ltd.     

Unique sudden onsets capture attention even when observers are in feature-search mode

Two sources of attentional capture have been proposed: stimulus-driven (exogenous) and goal-oriented (endogenous). A resolution between these modes of capture has not been straightforward. Even such a clearly exogenous event as the sudden onset of a stimulus can be said to capture attention endogenously if observers operate in singleton-detection mode rather than feature-search mode. In four experiments we show that a unique sudden onset captures attention even when observers are in feature-search mode. The displays were rapid serial visual presentation (RSVP) streams of differently coloured letters with the target letter defined by a specific colour. Distractors were four #s, one of the target colour, surrounding one of the non-target letters. Capture was substantially reduced when the onset of the distractor array was not unique because it was preceded by other sets of four grey # arrays in the RSVP stream. This provides unambiguous evidence that attention can be captured both exogenously and endogenously within a single task.     

Geometry,landmarks and the cerebral hemispheres: 2D spatial reorientation in split‐brain patients

A right‐hemispheric superiority in spatial encoding based on geometric cues has been largely documented in a variety of species, together with a left‐hemispheric specialization for encoding based on landmarks. In humans, hemispheric asymmetries for spatial encoding have been little explored. In this study, we compared a patient with a complete callosal resection (D.D.C.) and a patient with a wide callosal resection saving the splenium (A.P.), with healthy participants. In two 2D versions of the ‘reorientation task’, participants were asked to find the target corner of a rectangle‐shaped environment, by exploiting either geometric information alone or the combination of geometric and landmark information. In Experiment 1, the landmark consisted of a coloured side of the rectangle; in Experiment 2, this cue was replaced by a coloured disc located inside the rectangle. In both experiments, the rectangular shape ensured the geometric cue. D.D.C. was always unable to recall the target, whereas A.P. correctly solved the task when only the geometric information was available, without difference with respect to the controls. Importantly, the performance of A.P. did not differ from controls’ when the right hemisphere was tested with the landmark cues (the task being carried out using the left hand), whereas when the left hemisphere was tested (right‐hand session) his performance was worse than controls’ with the coloured side of the space, but it was better than controls’ with the coloured disc. The results are discussed comparing them with data collected on other species, and with theories of spatial processing.     

The context sensitivity of visual size perception varies across cultures

There is evidence that East Asian cultures have more context-sensitive styles of reasoning, memory, attention, and scene perception than Western cultures. Lower levels of the perceptual hierarchy seem likely to be similar in all cultures, however, so we compared context sensitivity in Japan with that in the UK using a rigorous psychophysical measure of the effects of centre-surround contrast on size discrimination. In both cultures context sensitivity was greater for females working in the social sciences than for males working in the mathematical sciences. More surprisingly, context sensitivity was also much greater in Japan than in the UK. These findings show that, even at low levels of the visual-processing hierarchy, context sensitivity varies across cultures, and they raise important issues for both vision scientists and cross-cultural psychologists.     

Blocking in Human Electrodermal Conditioning

Associative blocking in human conditioning was investigated using electrodermal and self-reported US expectancy measures. Previous null results using a design reported by Lovibond, Siddle, and Bond (1988) suggested that a clearly demarcated phase structure and visual cues with semantic content may have distracted attention from the experimental contingencies. Therefore the current experiment intermixed pre-training and compound training trials and masked the transition to the test phase to remove or reduce phase boundaries. Simple coloured squares were used as CSs to reduce semantic content. A significant blocking effect was observed on both the expectancy measure and on the electrodermal measure. Both results were due to improved transfer of conditioning to the target CS in the overshadowing control group in comparison to previous experiments. The results were interpreted as providing evidence that previous null results were due to failure of transfer of learning across clearly distinct phases. There was no evidence of a dissociation between the electrodermal and self-report measures. Theoretical and procedural implications for human Pavlovian conditioning are discussed.