Population norms of top sensory magnitudes and S. S. Stevens’ exponents

If S. S. Stevens’ exponents indicate the rates at which sensations grow with increases in sensory intensity, they ought to correlate with the population norms of top sensory magnitudes. Using a comprehensive sample of eight sensory dimensions, the tau coefficient of rank correlation between Stevens’ exponents and the medians of the top sensory magnitudes reported by 305 observers was found to be only +.15 (p>05). With the geometric means tau fell to ?.04. A split-half consistency check on the medians of the population norms suggested that they were not to blame for the low correlation. Direct comparisons of pairs of sensory dimensions on 146 additional observers produced results which confirmed the population norms. Since there is no way of comparing most of the top physical stimuli experienced in everyday life, it is not possible to make a joint prediction from exponents and top stimuli. S. S. Stevens’ exponents thus appear to have little predictive value outside the experimental conditions under which they were measured.     

Visual orientation preferences in the rat

An experiment was performed which demonstrated a preference in hooded rats for vertical rather than horizontal striatums. It was demonstrated that experience in discriminating between horizontal and vertical striations facilitates subsequent discrimination between squares and circles, regardless of which type of striation was positive in initial training. This finding has implications for theories of shape recognition, which are discussed.     

The relative intelligibility threshold for one's own name compared with other names

Two recent experiments (Moray, 1959; Oswald, Taylor and Treisman, 1960) have shown that in dichotic listening, and in sleep one's own name seems to be responded to selectively. We have shown for 10 subjects, each listening binaurally to the same recording of a list of their names repeated at random 10 times, and masked by noise, that the subject's own name had a significantly lower threshold than other names. The effect we found was not significantly different from the one found by Oswald et al. during sleep and by Moray for the dichotic situation.

These three experiments taken together suggest that the same pattern-analysing mechanism is involved in normal listening, dichotic listening to the rejected message, and in discrimination during sleep.     

On the failure to eliminate hypotheses in a conceptual task

This investigation examines the extent to which intelligent young adults seek (i) confirming evidence alone (enumerative induction) or (ii) confirming and discontinuing evidence (eliminative induction), in order to draw conclusions in a simple conceptual task. The experiment is designed so that use of confirming evidence alone will almost certainly lead to erroneous conclusions because (i) the correct concept is entailed by many more obvious ones, and (ii) the universe of possible instances (numbers) is infinite.

Six out of 29 subjects reached the correct conclusion without previous incorrect ones, 13 reached one incorrect conclusion, nine reached two or more incorrect conclusions, and one reached no conclusion. The results showed that those subjects, who reached two or more incorrect conclusions, were unable, or unwilling to test their hypotheses. The implications are discussed in relation to scientific thinking.     

The processing of positive and negative information

An affirmative statement which is known to be false and the complementary negative statement which is known to be true, provide the same information, i.e. that something is not the case. Similarly, an affirmative statement which is known to be true and the complementary negative statement which is known to be false, both imply that something is the case. (If P is false, not-P is true and if P is true, not-P is false.) Hence there are four kinds of statement (“conditions”): true affirmatives, false affirmatives, true negativee and false negatives, but only two kinds of information: positive and negative.

This experiment investigates the times taken to process information presented in these ways. The task was to select two alternative words which would make affirmative or negative conjunctive statements agree or conflict with given situations. The four conditions were presented six times in different serial orders, so that each occurred once in every block of four trials. The mean response times were: true affirmatives 8-99 sec, false affirmatives 11 19 sec., true negatives 12-58 sec, false negatives 15-17 sec. This order was the same at each of the six presentations of the conditions, the differences being significant at the 0 001 level in each case. There was a pronounced decline in errors (without knowledge of results) for three of the conditions. These results are discussed in relation to (i) the assumption of a positive set, established through a long learning process; (ii) the inferential nature of negative information in relation to experience; and (iii) the possible emotional effects of negative terms.     

PICTORIAL DEPTH PERCEPTION IN GHANAIAN CHILDREN1

Perception de la profondeur picturak chez les enfants ghanéens. — Une étude de la perception de la profondeur picturale chez 122 enfants ghanéens, fréquentant I'école primaire et âgés de 5 à 10 ans, a apporté les résultats suivants : — 1. l'identification correcte des représentations picturales des objets croît progressivement avec l'âge; ce qu'on peut interpréter comme un effet de l'expérience croissante avec les objets représentés. — 2. Les représentations picturales impliquant des abstractions, comme les lignes d'horizon ou les bords de route vues en perspective, sont fréquemment mal identifiées, quelque soit l'âge. Elles sont perçues bidimensionnellement et communément identifiées comme des objets, à qui est souvent attribuée une fonction d'utilité par rapport aux autres composantes du dessin. — 3. Un seul enfant donne des preuves constantes d'une perception tridimensionnelle. Les réponses des autres sujets suggèrent une perception bidimensionnelle. l'A. pense que la familiarité, culturellement déterminée, avec un matériel pictural est d'une importance critique pour le développement de la perception par les enfants de la profondeur picturale. — 4. Une analyse des explications relatives aux relations causales entre les é1éments picturaux suggère I'existence d'un schème commun de pensée, quelque soit l'âge. Ce schème est comparable à la “ pensée égocentrique ” telle que la conçoit Piaget, à condition qu'un contexte culturellement familier puisse entraîner différents schèmes de pensée.