Colours in black and white: the depiction of lightness and brightness in achromatic engravings before the invention of photography

What is it like to see the world in black and white? In the pioneer days of cinema, when movies displayed grey worlds, was it true that no 'colours' were actually seen? Did every object seen in those projections appear grey in the same way? The answer is obviously no--people in those glorious days were seeing a world full of light, shadows, and objects in which colours were expressed in terms of lightness. But the marvels of grey worlds have not always been so richly displayed. Before the invention of photography, the depiction of scenes in black-and-white had to face some technical and perceptual challenges. We have studied the technical and perceptual constraints that XV-XVIII century engravers had to face in order to translate actual colours into shades of grey. An indeterminacy principle is considered, according to which artists had to prefer the representation of some object or scene features over others (for example brightness over lightness). The reasons for this lay between the kind of grey scale technically available and the kind of information used in the construction of 3-D scenes. With the invention of photography, photomechanical reproductions, and new printing solutions, artists had at their disposal a continuous grey scale that greatly reduces the constraints of the indeterminacy principle.     

Footsteps and inchworms: illusions show that contrast affects apparent speed

A horizontal grey bar that drifts horizontally across a surround of black and white vertical stripes appears to stop and start as it crosses each stripe. A dark bar appears to slow down on a black stripe, where its edges have low contrast, and to accelerate on a white stripe, where its edges have high contrast. A light-grey bar appears to slow down on a white stripe and to accelerate on a black stripe. If the background luminances at the leading and trailing edges of the moving bar are the same, the bar appears to change speed, and if they are different the bar appears to change in length. A plaid surround can induce 2-D illusions that modulate the apparent direction, not just the speed, of moving squares. Thus, the motion salience of a moving edge depends critically on its instantaneous contrast against the background.     

Attitudes of learner drivers toward safety at level crossings: Do they change after a 360° video-based educational intervention?

In light of the growing number of level crossing accidents and the limited prevention programmes, this study examined relationships among attitudes toward traffic rules, impulsiveness, and behavioural intentions at level crossings. It explored the behavioural effects of an educational programme newly developed within the framework of the Croatian national safety project “Implementation of measures to improve the safety of the most vulnerable traffic participants at level crossings“. The programme aimed to change risky attitudes and behavioural intentions of learner drivers at level crossings. It consists of a safety lecture accompanied by pictures, videos and the exposition to a 3D virtual reality film shot at a real level crossing, which allows the participant to experience, from the driver’s perspective, safe and risky crossings. The programme was implemented in 11 driving schools. First, 285 participants (62.8% men) answered a questionnaire measuring safety attitudes toward traffic and impulsiveness, then they attended a lecture and participated in the virtual reality experience. Finally, they answered a questionnaire measuring planned future behaviour at level crossings. The results showed that attitudes toward level crossing risk significantly predicted intended driving behaviour at level crossings. Furthermore, the 360° video-based educational intervention altered the relationships connecting attitudes toward level crossings and risky driving behaviour at level crossings. The practical implications of these results are discussed.     

Signalled and unsignalled avoidance impairments following noradrenaline depletion with DSP4: An hypothesis incorporating and associative and a non-associative factor

Four experiments were performed to investigate the effect of a single prior administration of the selective noradrenaline neurotoxin, DSP4 (50 md/kg, i.p.), upon signalled and unisgnalled variations of the two-way active avoidance procedure. Noradrenaline depletio following DSP4 caused a significant impairment in the acquisition but not in the retention of signalled avoidance. Two unsignalled discrete trial avoidance procedures were used, one of which the 50/10 procedure, was designed to be considerably more difficult than the other, the 50/40 procedure. DSP4- treated rats were found to be impaired on the difficult 50/10 task but not on the 50/40 task. It was also shown that the DSP4 group in the 50/10 experiment made fewer crossings that did not result in shock postponement ('nonreinforced' or intertrial crossings) while in the 50/40 experiment the DSP4 group in the 50/10 experiment made fewer crossings that did not result in shock postponement ('nonreinforced' or 'intertrial' crossings) while in the 50/40 experiment the DSPS group made more 'intertrial' crossings. Response latencies were not significantly altered as a result of the treatment in both instances. The results of the present experiments in conjunction with much accumulate evidence from several other investigations were assimilated in order to develop an hypothesis to account for the consistent signalled two-way avoidance deficits resulting from DSP4 administration. This hypothesis incorporates two main components: (1) It may be that DSP4-treated rats are unable to develop the correct coping behaviour required in the stressful task confronting it, i.e. they fail to make the appropriate crossing (running) respose whether an escape or an avoidance response; (2) It is possible that DSP4-treated rats may fail to associate adequately a successful avoidance response with either the tone that signals shock or the postponement of shock.     

Factors explaining driver yielding behaviour towards pedestrians at courtesy crossings

Courtesy crossings are pedestrian crossing facilities where drivers are not legally required to stop for pedestrians, but are encouraged to do so by design elements such as stripes, coloured or textured road surfaces, visual narrowings of the carriageway, and ramps. There is little empirical evidence on drivers' behaviour or guidance on how to design these crossings. This paper analysed data for 937 interactions between drivers and pedestrians at 20 crossings across England, comparing driver yielding behaviour at courtesy crossings and at zebras (marked unsignalised crossings, where drivers are legally required to stop); and identifying the design elements associated with yielding behaviour at courtesy crossings. The analysis controlled for crossing stage; characteristics and situation of pedestrians and vehicles; characteristics of the road and site; and time context. Driver yielding behaviour was analysed for each separate traffic lane that pedestrians need to cross. We found that all four design elements considered (stripes, coloured/textured surface, visual narrowing, and ramps) increased the propensity of the first vehicle to stop and of any vehicle to stop. A before-after analysis then showed that adding a new element (stripes) to a courtesy crossing led to an increase in yielding rates from 20% to 97%. Overall, we found evidence supporting the use of multiple design elements in courtesy crossings. We discuss the implications of these findings for transport policy and urban design.     

Word learning is 'smart': evidence that conceptual information affects preschoolers' extension of novel words

We examined electrophysiological correlates of conscious change detection versus change blindness for equivalent displays. Observers had to detect any changes, across a visual interruption, between a pair of successive displays. Each display comprised grey circles on a background of alternate black and white stripes. Foreground changes arose when light-grey circles turned dark-grey and vice-versa. Physically stronger background changes arose when all black stripes turned white and vice-versa. Despite their physical strength, background changes were undetected unless attention was directed to them, whereas foreground changes were invariably seen. Event-related potentials revealed that the P300 component was suppressed for unseen background changes, as compared with the same changes when seen. This effect arose first over frontal sites, and then spread to parietal sites. These results extend recent fMRI findings that fronto-parietal activation is associated with conscious visual change detection, to reveal the timing of these neural correlates.     

Capturing lightness between contours

Homogeneously coloured bars may exhibit lightness differences at the intersections. A well-known example is the Hermann grid illusion, where crossing white bars on a black background show dark patches at the crossings. Jung (1973, Handbook of Sensory Physiology volume VII/3, pp 1-152) found that the dark patches persist when thin outlines are drawn at the intersections, and are even visible in foveal vision. Recently, it has been shown that making distortions to the contours of a Hermann grid-like configuration results in the disappearance of the illusory dark spots (Geier et al, 2008 Perception 37 651 665). We show that thin outlines at the crossings of the distorted Hermann grid induce lightness differences in the same direction as in the original Hermann grid illusion, even in foveal vision and in displays consisting of two crossing bars. Our experiments reveal that the induced lightness differences are independent of the luminance polarity and shape of the contours at the intersection. We suggest that the effect results from lateral inhibition and an additional spreading and capturing of these differences between luminance contours. A similar capturing between collinear contours may play a role in peripheral vision in the original Hermann grid.     

Determinants of perceived surface transparency in two-dimensional achromatic textured patterns

Achromatic transparency in 2-D surfaces composed of three adjacent areas, one created from the others, occurs when in the created area it is possible to see the two colours of the adjacent areas. Displays with two white and black intersecting bars were produced to verify the possibility of perceiving transparency in the intersection area when this was subdivided into a different number of white and black diamonds. By increasing the spatial frequency of the elements in the intersection area we investigated the impression of transparency, and found that (i) the impression of transparency increases up to a spatial frequency of 10 cycles deg(-1) and then levels off, (ii) there is a transition from a perception of transparency in which white and black are well discriminable to a perception in which a perceptually uniform grey is seen, (iii) the perception of transparency occurring when colours are discriminated seems consistent with Helson's area-luminance hypothesis [1964, in Adaptation Level Theory (New York: Harper & Row) pp 282-292], according to which the increase of spatial frequency determines the transition from the phenomenon of contrast to that of assimilation.     

Black Box Arguments

“Black box argument” is a metaphor for modular components of argumentative discussion that are, within a particular discussion, not open to expansion. In public policy debate such as the controversy over abstinence-only sex education, scientific conclusions enter the discourse as black boxes consisting of a result returned from an external and largely impenetrable process. In one way of looking at black box arguments, there is nothing fundamentally new for the argumentation theorist: A black box argument is very like any other appeal to authority, and what might be said about any particular form of black box will turn out to be a particularized version of what might be said about evaluating arguments based on authority. But in another way of looking at black box arguments, they are a constantly evolving technology for coming to conclusions and making these conclusions broadly acceptable. Black boxes are to argumentation what material inventions are to engineering and related sciences. They are anchored in and constrained by fundamental natural processes, but they are also new things that require theoretical explication and practical assessment.     

Can boundary crossings in clinical supervision be beneficial?

Published studies have addressed boundary violations by clinical supervisors, but boundary crossings, particularly those deemed positive by supervisees, have not received much attention. Eleven trainees in APA-accredited doctoral programs in clinical and counseling psychology were interviewed regarding positive boundary crossings (PBCs) they experienced with clinical supervisors. Interview data were analyzed using Consensual Qualitative Research. Examples of PBCs included socializing with supervisors outside the office, sharing car rides, and supervisor self-disclosure. Typically, supervisees did not discuss the PBC with their supervisors because they were uncomfortable doing so, felt that the PBC was normal, or felt that processing such issues was not part of the supervisor’s style. Most supervisees viewed the PBCs as enhancing the supervisory relationship and their clinical training; however, some participants reported that the PBCs created role confusion. The results suggest that there are legitimate reasons for supervisors to be scrupulous about their boundaries with supervisees; however, supervisors who hold rigid boundaries can deprive supervisees of deeper mentoring relationships or a more authentic emotional relationship that can be valuable to supervisees learning how to provide psychotherapy.     

An orientation anisotropy in induced brightness

It is shown that an orientation anisotropy exists for the magnitude of induced brightness in a cruciform stimulus consisting of a grey test patch positioned at the intersection of two inducing bars, one black and one white, oriented at right angles to each other. When the cruciform was oriented such that the white bar was horizontal, the grey patch appeared darker than when the same cruciform was oriented such that the white bar was vertical. The contribution of the black and white inducing bars towards the brightness of the test patch was investigated. A simple mathematical function, which took into account both the contribution of the two component inducing bars and the orientation anisotropy, was fitted to the data. No consistent orientation anisotropy was found with inducing stimuli at oblique orientations.     

Changes in colour and location as cues of generative transmission in perception of causality

Observers viewed modified launching effect displays containing a spatial gap between the final location of the launcher (a black square) and the initial location of the target (a black outline square with a white interior). In some conditions, a set of stationary objects (black outline squares with white interiors) filled the spatial gap, and these objects began changing colour upon contact from the launcher. The colour changes could involve all gap objects turning black, the first gap object turning dark grey and subsequent gap objects turning successively lighter grey, or first gap object turning light grey and subsequent gap objects turning successively darker grey. The colour changes could move from the launcher to the target or from the target to the launcher. The gap objects could also remain unchanged. Participants rated whether the launcher caused subsequent motion of the target and how much force the launcher imparted to the target. The sequence of colour changes, and the sequence of locations in which colour changes occurred, influenced ratings; sequences of colour changes consistent with the idea that influence of the launcher was transmitted across gap objects to the target resulted in higher ratings. Implications for visual perception of causality are discussed.     

Assessing driver acceptance of Intelligent Transport Systems in the context of railway level crossings

Intelligent Transport Systems (ITS) have the potential to substantially reduce the number of crashes caused by human errors at railway levels crossings. Such systems, however, will only exert an influence on driving behaviour if they are accepted by the driver. This study aimed at assessing driver acceptance of different ITS interventions designed to enhance driver behaviour at railway crossings. Fifty-eight participants, divided into three groups, took part in a driving simulator study in which three ITS devices were tested: an in-vehicle visual ITS, an in-vehicle audio ITS, and an on-road valet system. Driver acceptance of each ITS intervention was assessed in a questionnaire guided by the Technology Acceptance Model and the Theory of Planned Behaviour. Overall, results indicated that the strongest intentions to use the ITS devices belonged to participants exposed to the road-based valet system at passive crossings. The utility of both models in explaining drivers’ intention to use the systems is discussed, with results showing greater support for the Theory of Planned Behaviour. Directions for future studies, along with strategies that target attitudes and subjective norms to increase drivers’ behavioural intentions, are also discussed.     

Visible Speech as a Function of Image Quality: Effects of Display Parameters on Lipreading Ability

Two experiments are reported that examine effects of certain visual display parameters on subjects' ability to lipread numbers. The quality of the image of the speaker's face is altered by varying temporal resolution (frame rate), spatial resolution (number of pixels) and contrast resolution (number of grey scale levels). In Experiment 1, combinations of these variables are examined in a repeated measures design and reliable effects of reducing both frame rate and number of grey levels are evident. In Experiment 2, the frame rate and grey scale settings are factorially combined on a between-subjects basis, and practice is given so that subjects can adapt to the display conditions to which they are exposed. Effects of frame rate and grey scale are again statistically significant, and additive. Lipreading performance improves over the short duration of the experiment, but both image variables continue to affect performance. The effect size of the grey scale factor decreases with practice, but not that of frame rate. The results are discussed with regard to the kinds of relevant visual cues that may be affected by image degradation. Implications for the planned development of low cost digital communication are also considered. Trading off one image variable at the expense of another may be necessary to meet bandwidth limitations, and data such as those presented will be necessary to decide on a combination of parameter values to satisfy human performance and technical criteria.     

The safety and conspicuity of pedestrian crossing at roundabouts: The effect of median refuge island and zebra markings

Roundabouts are one of the most used road intersections because, compared to signalized ones, they reduce conflict points between traffic flows and moderate driving speed. Great attention should also be paid to vulnerable road users at roundabouts. According to accident statistics, in fact, accessibility of pedestrians and cyclists is not always ensured.This paper has evaluated the effects on the visibility of pedestrian crossing before and after the displacement of zebra markings, moved before intersections, and the introduction of media refuge islands and “Yield here to pedestrians” vertical signs. The above effects have been assessed by before-after analysis of speed and visual behaviour of drivers approaching the crosswalk.Moreover, the analysis of the drivers’ eye movements has highlighted the most salient elements of the pedestrian crossing. The relation between the drivers’ visual behaviour and the vehicle speed have also been calculated. Results have confirmed that the intervention carried out has increased both visibility and safety of the studied pedestrian crosswalks.Zebra markings and the median refuge island have turned out to be the most glanced elements, respectively seen by 93.75% and 56.25% of the drivers, followed by the “Yield here to pedestrians” vertical sign. The mean distance of first fixation of the crosswalk increased from 21.98 m before the intervention, to 40.69 m after it. The drivers perceived the pedestrian crossings from a longer distance after the intervention, and they continued to glance at the crosswalk while approaching it, enhancing their visual attention.     

A within-subject design of comparison of waiting time of pedestrians before crossing three successive road crossings

This study is a partial replication of the work of Hamed (2001) who found a negative correlation between waiting time of pedestrians before crossing the first and the second stage of a road divided by an island. The innovation of the current study is an addition of testing the waiting time before crossing a third successive crosswalk. The research is based on examining the correlation between the waiting times of pedestrians before each stage of crossing a triple-crossing. The research was conducted in two different types of three successive crossings: (1) with a narrow or (2) with a wide refuge island dividing between the two parts of the main road. We hypothesized that in a narrow island condition the correlation between the waiting time of the first and the second crossings will be negative; a finding that would have replicated Hamed’s finding. However, in a wide island condition, so that the two-stage crossing will be perceived by the pedestrian as two separate units, the correlation between the waiting time in the first and the second crossings would be positive. More than 750 people (of which 54% were female) were observed crossing junctions with a triple-stage crossings in three different locations in the center of Israel (two with wide islands and one with a narrow island). The waiting time before crossing each part of the road was measured by two experienced observers. The mean waiting time beyond individual differences was 6.00, 5.76 and 0.79 s at the first, second and third crossings respectively. Our results are not in line with those of Hamed (2001). At the junction with the narrow island no correlation between the waiting time of the first and the second crossing was found. A positive correlation has been found between the waiting time of the first and the second crossing in the condition of the wide refuge island. In all locations a positive correlation has been found between the waiting times at the second and third crossings. These findings lead to an optional explanation that the width of the refuge island determines the way in which the pedestrian perceives the task of crossing two-stage crossings. These findings support a possible explanation by a newly suggested model – Renewed Patience Model. The implications of the research and other methodological issues are discussed.     

Facial Recognition: Weapon Effect and Attentional Focus1

The present experiment investigated the hypothesis that a weapon can serve as a cue that will interfere with the eyewitness’ encoding of the weapon-holder's facial features. Extrapolating from Easterbrook's cue utilization hypothesis, an interaction between arousal and attentional focus was predicted. White female college students played a bogus visual discrimination game in which they saw a total of 24 target photos: six black targets holding a weapon in their hands, six white targets holding weapons, six black targets holding objects other than weapons, and six white targets holding objects other than weapons. Subjects were randomly assigned to view the photos while experiencing white noise and threat of electric shock (high arousal) or without such factors (low arousal). Subjects were also randomly assigned to one of four attentional focus levels: face focus, hand focus, background focus, and free focus. A signal detection-type task provided an assessment of identification accuracy. The data revealed a significant “weapon effect”: Subjects were better at identifying photos of targets who were not holding a weapon than they were at identifying photos of targets who were holding a weapon. Focus of attention and race of target also significantly affected recognition accuracy, as did arousal in one of two analyses. No support was found, however, for the predicted interaction between arousal and attentional focus. Finally, subjects showed a strong criterion shift according to the race of target; they were much more likely to make a “seen before” response to other-race (black) faces than to same-race faces.     

Social preference of female gerbils (Meriones unguiculatus) as influenced by coat color of males

Female gerbils (Meriones unguiculatus) of three distinct coat colors (agouti, black, and sandy or pink-eyed dilution) were tested in a Y-maze whose arms led to compartments containing unfamiliar male gerbils of varying coat colors. The stimulus animals were separated from the females by a Plexiglas door. The trials lasted for 2 min and each female was exposed to the following four combinations: two males of the same coloring as the female; one male of the same color and another of a different color from the female; both males of different color from the female. The number of crossings to the left and right arms was relayed by photocells to an IBM PC computer. The results indicate that agouti females preferred visiting the arm occupied by agouti males while those of the other coat colors showed no preference for the "wild-type" males. Instead, sandy and black female gerbils preferred to be in proximity with those of non-wild types.     

The colors of the alphabet: naturally-biased associations between shape and color

Many letters of the alphabet are consistently mapped to specific colors in English-speaking adults, both in the general population and in individuals with grapheme-color synaesthesia who perceive letters in color. Here, across six experiments, we tested the ubiquity of the color/letter associations with typically developing toddlers, literate children, and adults. We found that pre-literate children associate O with white and X with black and discovered that they also associate I and ameboid nonsense shapes with white; Z and jagged nonsense shapes with black; and C with yellow; but do not make a number of other associations (B blue; Y yellow; A red; G green) seen in literate children and adults. The toddlers' mappings were based on the shape and not the sound of the letter. The results suggest that sensory cortical organization initially binds specific colors to some specific shapes and that learning to read can induce additional associations, likely through the influence of higher order networks as letters take on meaning.     

Stimulus change effects of forcing on maze arm selection in hamsters

Hamsters were forced to enter one arm of a T-maze on four succesive runs by means of either a grey door of the same brightness as the rest of the apparatus or by a black or white door. During four successive free choices the subjects entered the previously blocked arm significantly more often following forcing with the black or white door.