APPARENT WEIGHT DIFFERENCES AS A SOURCE OF AFTER-EFFECTS

Two experiments are reported. In the first, the influence of stimulus size on apparent weight, i.e., the size-weight illusion, was scaled. The relationship between heaviness and size could be described by a simple power function. In the second experiment it was demonstrated that the illusory weight differences give rise to aftereffects. The size of the after-effect increased monotonically with the amount of apparent weight difference.     

CHANGES IN REPEATED REPRODUCTION OF WEIGHT AS A FUNCTION OF ADAPTATION LEVEL

The retention of memorized weights was repeatedly tested by the reproduction method, the subject's state of adaptation for weight being systematically changed between the tests. The reproduction scores were found to vary as approximately linear functions of the adaptation level. This relationship was unaffected by changes in the degree of learning of the memorized weight and in several other variables. The 'anchoring' and retention of weight, and different indicators of adaptation level, are discussed.     

CHANGES IN REPEATED REPRODUCTION OF PITCH AS A FUNCTION OF INTERPOLATED STIMULI

The retention of memorized pitches was tested repeatedly by systematically changing pitches being interpolated between the successive reproduction tests. The reproductions changed regularly in the direction of the interpolated stimuli. The relationship between the reproduction scores and the cps-means of the interpolated pitch-series could be described fairly accurately by power functions. Some connections between the present results and the results of previous experiments on memory and scaling are discussed.     

CHANGES IN TEST CHARACTERISTICS AS A FUNCTION OF LEARNING OF THE OBJECT-TASK

M ikkonen V. Changes in test characteristics as a function of learning of the object-task. Scand. J. Psychol ., 1972, 13 , 306–313.—Two verbal learning experiments, one consisting of six free recall trials, the other of six recognitions, are analysed as performance tests in order to follow the changes in test characteristics with increasing mean performance. In general, the items in the tasks form more consistent tests with greater degree of learning; coefficient alpha as a measure of reliability improves from the level of 0.02–0.50 to that of 0.70–0.85. Internal consistency can further be increased by item selection especially at low levels of performance. Practical implications of the results are discussed and a few recommendations presented.     

THE INFLUENCE OF ALCOHOL ON THE DETECTION OF LIGHT SIGNALS IN DIFFERENT PARTS OF THE VISUAL FIELD

6 subjects performed 12 times each a signal detection task lasting 40 minutes in parallel with a simple tracking task. They reported every 2nd second whether or not a signal was given in any one of 10 widely spaced locations. 0.5 or 1.0 ml alcohol/kg body weight (or no alcohol) was given 35–25 minutes prior to the task. Hit rate ( HR ) covaried with tracking efficiency; FAR was uniformly low. Variation in signal probability had no effect. Alcohol had a strong and uniform effect on 3 "experienced" subjects, reducing HR for all signals and producing a funneling effect, but had little effect on the performance of 3 "inexperienced" subjects. Motivational variables which may account for the individual differences are discussed.     

ON THE NONVISUAL CUES CONTROLLING THROWlNG MOVEMENTS

M ikkonen , V. & K olehmainen , K. On the nonvisual cues controlling throwing movements. Scand. J. Psychol ., 1968, 9, 169–176.—When position of subject's head is varied (his eyes fixating the target) in dart throwing experiments, systematic errors occur in the throws in the direction in which the head is turned. Subjects trained to hit the target with the head turned to the side, and then allowed to throw with the face towards the target, make errors in the direction opposite to that in which the head was turned during training. The most recently learned relationship between head and hand thus tends to guide the throws. Changes occur primarily in the direction of the throwing movement, the starting position of the throwing hand being relatively stable.