Black Rectangle Research Articles

Bands in Cellular Blue Nevus-Reply

In Reply.— Our experience on the relationship between cellular blue nevus and nerves is different from that of Dr Bourland. We have observed invasion of nerves by cellular blue nevus cells. In fact, a cell containing melanosomes, indistinguishable from the nevus cells present outside the nerve, can be seen in the Figure (close to the banded structure in black rectangle in the uppermost part of the electron micrograph).1This has also been reported by other workers, both in experimentally induced nevi in animals2and humans.3 In contrast to Dr Bourland's observations, ultrastructural evidence of degeneration of Schwann cells and axons was seen in almost every nerve within the cellular blue nevi of our three patients. Figure 1 in our report showed multiple layers of basement membrane surrounding a Schwann cell from a nerve within a cellular blue nevus. Such changes have been considered to result from repeated

The inability of Octopus vulgaris to discriminate monocularly between oblique rectangles.

Octopuses were trained monocularly to discriminate between pairs of rectangles presented successively. In Experiment 1 eleven octopuses that had reached a high level of performance on a horizontal/vertical discrimination were unable to discriminate when the rectangles were presented as mirror-image obliques. In Experiment 2 ten octopuses began by discriminating well between black and white rectangles that were mirror-image obliques. This high level of discrimination continued when the black oblique was replaced by a dark grey one but performance fell to chance level when the dark grey was replaced by a pale grey oblique. In Experiment 3 eleven octopuses successfully discriminated between an oblique and a vertical rectangle but they performed at chance level when the mirror-image oblique was substituted for the vertical rectangle. It is concluded that Octopus vulgaris is unable to discriminate between mirror-image oblique rectangles presented successively.

Two-cue discrimination learning by pigtail monkeys

Twelve monkeys were given a discrimination between black vertical and white horizontal rectangles and then given preference tests with original positive and negative stimuli paired with white vertical, black horizontal, white and black diagonal rectangles, and white and black circles. Ss responded more to circles than to other preference stimuli early in preference testing but less later, suggesting a novelty effect. Preference for the reinforced brightness was significantly higher than for the reinforced orientation.

PERCEPTION OF MOVING FIGURES 1, ON THE REDUCTION PHENOMENA

An oblong rectangle moving horizontally shows decrease in its perceived length parallel to the moving difrection, when the moving speed increases up to a certain point. Present study concerns with the quantitative relationship between the perceived size of a moving figure and its moving speed.A black rectangle projected on a screen moves horizontally. The speed ranges from 32.2°/sec to 120.6°/sec. A method of reproduction is used to estimate the perceived size of a moving figure. Twelve students serve as Ss. Possible bias owing to the method used is also measured. Four out of five stimuli used tend to show a similar tendency when possible bias is corrected. An equation showing the relationship between perceived size and moving speed is suggested.

Processing of tachistoscopic displays with controlled order of characters and spaces

The task used was designed to force Ss consistently to process the letters of a tachistoscopic display in the same spatial order, if Ss are able to process the letters in a brief display serially and if Ss have enough voluntary control over the selection of a processing order to use the order chosen by the E. In the main series of experiments the set of slides shown in each session included slides having a blank space in some position in the linear array of letters. For control, no-blank slides, a sharp, monotonic decrease in the percentage of correct detections of a signal letter with distance of the signal letter from the focusing dot was obtained. An unexpected result from the slides having a blank space was that detection of the signal letter was considerably more accurate on the slides having a blank space immediately following the signal letter than on the control slides having no blank space or the slides having a blank space immediately before the signal letter in the processing order. In one experiment blank spaces were replaced by black rectangles with no substantial change in the pattern of results. The results from the slides having a blank space or a black rectangle were interpreted as indicating that the onset of processing the image of a letter was determined by the distance in the display from the focusing dot to the letter and that the duration of processing an image of a letter was determined by the distance in the display from the letter to the next letter in the processing order.

The retinal after-image of induced movement.

This note describes a technique for obtaining a retinal after-image of a stationary object that appears to oscillate rapidly in a fixed path. The illusion involved, commonly referred to as induced movement (LM), is the observation of movement of an object in a direction opposite to that of an objectively moving background. The device for obtaining IM was described previously in greater derail (Vetter, 1965). A vertical display, i.e., a board on each side of which is a black dot, centered, and enclosed by a black verticallyoriented rectangle, is rotated on a record turntable. The rectangles are positioned with regard to each other such that, although the dots fall in identical positions on the two sides of the board one dot is near the top while the second is near the bottom of its respective rectangle. During rapid rotation (e.g., 100 rpm) a single dot is perceived as oscillating (IM) in a direction opposite that shown by the apparent (phi) movement of the rectangles. For present purposes the dots are replaced by two apertures 2 cm. in diameter. The spacing between the cwo sides is increased to 7 cm. so that a 25-w, 110-VAC bulb by being suspended from above may be exposed through the aperture of each side. A spot of light can then be seen within the rectangles although the bulb remains stationary during rotation. To allow for a maximum degree of IM under conditions thar also yield an afterimage, two further changes are necessary. First, only a minimum degree of room illumination is desirable. (Some light is needed to perceive the rectangles.) Secondly, since fixation of the bulb does not result in much IM a point at the top and center of the display is fixated during rotation. When the above conditions are met, the spot of light appears to oscillate vertically at a continuous rate, travelling a distance about equal in length to the inner vertical borders of the rectangles (16.5 cm.) when viewed at eye-level at a distance of 1.35 m. Following 4 min. of binocular fixation a recognizable after-image of the point is seen when the eyes are closed. It is about the size and shape of the after-imspc obtained when the apertures are fixated and the display is not rotating. This indicates [hat relatively slow, sweeping eye movements (e.g., due to involuntary follorving of the rectangles) are not occurring during the perception of IM. If overt, gross eye movements were, in part, responsible for the illusion, one would expect that streaking on rhe retina would exist and correspond to some extent to the subjective distance travelled by the object (6 to 8 of visual angle). Since such was not the case it is suggested [cf. previous observations (Vetter, 1965)] thar some other mechanism such as, e.g., implicit eye movements, is more likely involved in producing IM.

Responses of untrained octopuses to various figures and the effect of removal of the vertical lobe.

Octopuses that have not been trained to come out to attack figures moving in the visual field do so only on some occasions. With repeated unrewarded trials at long intervals the frequency of attack does not increase even if the animals are left without food. There may be a slight decrease (‘habituation’). The tendency to attack is not the same throughout the day, but is greater in the evening. The tendency to attack moving figures is greatly increased during the period of 1 to 2 h after an octopus has been fed, even if the food is given in the home and not at the place where the figures are shown. Other things being equal, there are marked differences in the tendency to attack various moving figures. Crabs were attacked more often than any other figures tested. Circles were attacked more than rectangles of the same area, white figures more than black and small rectangles more than large. There was some evidence of a tendency to attack vertical more than horizontal rectangles (both being moved vertically). The effect of removal of the vertical lobe is to change the previous tendency of the animals to attack. Of thirty animals operated, eighteen attacked more after operation, twelve attacked less. Those that attacked more afterwards had previously attacked on 26.5% of occasions, those that attacked less on 60.5% of occasions. The operation thus removes at least part of the memories set up before operation. Those animals in which these memories tended to promote attack will come out less often after operation and vice versa.

現象的速度に及ぼす挾角の影響について

The present experiments were conducted to find out how the change in the apparent length of and aperture caused by attaching a pair of arrowheads on both ends of it, affects the phenomenal velocity of moving objects behind the aperture.Two apparatus (one for the standard and the other for the comparison) are placed in front of the subject on a table in a dark room, and illuminated by a reflector lamp. An aperture (3mm × 15cm) is horizontally opened in the middle of a white paper (30cm × 63cm) which is placed in front of each of the apparatus. Behind the aperture is a moving belt on which black rectangles (3mm × 5mm) are distributed at an interval of 5mm. Arrowheads with different angles and with 6cm sides are attached on both ends of the aperture. The belt of the standard apparatus moves with the speed of 5cm/sec, and the subject is asked to adjust the visual speed of the moving objects in the comparison-apparatus to that of the standard.Results :Exp. 1. Without attached arrowheads the decrease of the aperture length resulted in the increase of the phenomenal velocity of moving objects.Wxp. 2. With arrowheads pointing towards the center of the aperture the object was seen faster than with arrowheads pointing away from the center of the aperture.Exp. 3. The presence of the arrowheads always increased the phenomenal velocity.Exp. 4. The effect of putting two lines perpendicular to the edge of the aperture on visual velocity was smaller than those of any other cases.Exp. 5, 6. From the results based on data from the measurement of illusion caused by a pair of arrowheads, we could not recognize that the change of the aperture's apparent length caused by illusion had any effect on the phenomenal velocity.The difference in the distance from the ends of the arrowheads to the center of the aperture had no effect on the phenomenal velocity.The difference in the area of the total extensions sustained by two arrowheads had a considerable effect on the phenomenal velocity.Exp. 7. The apparent length of the aperture was shortened by the motion of the moving objects.Exp. 8, 9. The intenser the figures showed the character as a reference-point (‘an anchorage’) to the moving objects, the more the phenomenal velocity increased.Conclusion :The effect of arrowheads attached to both ends of the aperture on the phenomenal velocity, would be generally caused by the following two factors : (1) the difference in the total extension sustained by two arrowheads, and (2) the strength acting as a reference-point to the moving objects. so far as our experimental condition were concerned, the change of the aperture's apparent length by illusion did not act as a factor in the change of the phenomenal velocity.

Visual Responses by Octopus to Crabs and Other Figures Before and After Training

ABSTRACT Octopuses were fed for some days with fishes in their homes at one end of the tank, and the effect of figures shown at the opposite end was tested. Any small moving object may then be attacked, but the probability of attack is low and the delay long. Crabs and a black horizontal rectangle were attacked more often than other figures. If a figure is withdrawn on the occasions when it is attacked, then the probability of attacks remains low and may slowly decrease. If the octopus is allowed to eat crabs the probability of attacks on them quickly rises towards unity. If food is given when some other figure (say a black vertical rectangle) is attacked, then this figure will later be attacked. An octopus makes attacks more regularly on a figure that has recently been associated with food than on any other figure. This learning to attack a given figure can take place after removal of most of the vertical lobe, but the learning is slower and responses less accurate than in the normal animal. Octopuses from which the vertical lobe has been removed attack crabs more readily than other figures. The system that ensures attack therefore resides elsewhere, probably in the optic lobes. If shocks are given when a previously neutral figure is attacked, then the probability of further attacks on this figure rapidly approaches zero. Attacks on other figures or crabs remain frequent. If the vertical lobe is then removed, no attacks are made on such an originally neutral figure. If a figure that has been associated with food is then rewarded with shocks, the probability of attack falls more slowly than if the figure had been neutral. If the vertical lobe is now removed, the frequency of attacks rises. The memory preventing attack is therefore partly resident in the vertical lobe. The greater the amount of previous training to attack, the more slowly does the animal learn not to attack. This applies also if the training to attack is given after vertical lobe removal. After vertical lobe removal, shocks given when crabs are attacked rapidly reduce the probability of attack if the octopus had not previously eaten crabs while in the laboratory. If such feeding had taken place, the probability of attack falls only slowly without the vertical lobes. The experiments show that information stores associating a given figure with either food or shock can be set up after removal of the vertical lobes but tend to dissipate more rapidly than in a normal octopus.

Thomas Milne's Land Utilization Map of the London Area in 1800

To make A land utilization map of piece of country, the modern geographer selects base-map showing field boundaries. By inspection of the ground, he inserts key letter within each field to show its use, such as A for arable land, M for meadowland, H for heathland, and so on. He then prepares coloured map, with arable land in brown, meadowland in light green, forest in dark green, heath? land in yellow, gardens in purple and agriculturally unproductive land in red. This procedure derives from the method adopted by the Land Utilization Survey of Britain to record the face of Britain in the years 1930-8. The use of letters and colours on the published land use maps of this Survey was not entirely new, how? ever, for as early as 1800 Thomas Milne had prepared for publication handcoloured, engraved map of the London area which makes use of this technique. map, on scale of 2 inches to 1 mile, is engraved on six plates, each n34 by 15 inches. It bears the title Milne's Plan of the Cities of London and Westminster, circumadjacent Towns and Parishes c 11th March An area of about 260 square miles, extending from Harrow Weald to Woodford and from Hampton-on-Thames to Sundridge Park is covered by the map. The map records the use of each field by means of an inserted letter and an overpainted colour. These make it possible to distinguish no less than twelve different types of land use; as several are sub-divided, seventeen categories in all may be distinguished. Arable land, when enclosed, is shown by the italic letter a and pale brown colour not unlike the one used by the Land Utilization Survey century and quarter later. Enclosed meadow and pasture are shown exactly as on the later Survey, by the letter m and light green colouring. Woodland is shown by the letter w, tree symbols in the form of tiny circles, and dark green colour. Enclosed market gardens receive the letter g and light blue colour; nurseries n and orange colour. Orchards and osier-beds share the letter o and blue colouring, so that the map reader needs to judge from the nearness of the field to the river which of the two is intended. Paddocks or little parks are represented by the letter p and pink colour; the position of the residence within the park is shown by black rectangle. Drained marshland pasture has the letters ma and greygreen colouring. Common fields, with their admixture of small strip-fields used for diverse purposes, present difficult problem to the cartographer. One-third of the agricultural land of the London area still remained unenclosed in 1800. Milne showed great care and skill in representing, within the limits of scale, the variety of land use in common fields. The letters caf designate common arable fields. They are coloured brown if wholly arable, and bear conventionalized brown and green stripes if there is considerable admixture of grassland strips with the arable. Common meadows bear the letters cmf and solid green colouring, or green and brown bands as might be appropriate. Common market-garden fields are shown by the letters cgf and blue colouring, or by blue and brown bands. Great care

Photographic Granularity and Graininess IV Visual Acuity Thresholds; Dynamic versus Static Assumptions*

The distances at which a series of rectangular test objects are visible were determined experimentally. These test objects were black opaque rectangles having variable length-width ratios and were viewed against a trans-luminated background. Using these data, and an assumed nystagmic motion of the eyeball, the summated temporal illuminance gradients on the retina were computed. These values were found to be essentially constant, even though the length-width ratios of the test objects varied from 1 to 4050. Assuming a motionless eyeball, that is, perfect fixation, the summated values of ΔI were computed for the same observational conditions, ΔI being defined as the difference between the average illuminance incident on adjacent cones in the retinal mosaic. The values of summated ΔI are not constant. Since all of these test objects were just visible at the distance measured, they may be considered as being equal to each other with respect to their ability to excite a threshold neural response. It seems reasonable to conclude, therefore, that since the values of the summated temporal gradients are constant they are the most significant indices of the relative magnitudes of the neural responses. In our opinion these results lend considerable support to the assumption that the perception of inhomogeneities of luminance in the visual field is dependent directly upon the temporal illuminance gradients to which the retinal receptors are subjected by virtue of the movement of the image with respect to the retinal mosaic.