Dianne B. Wuillemin

On the failure to recognize the back of one's own hand.

Subjects were able to discriminate photographs of their own hands from other hand photographs but were unable to recognize their hands amongst a group of other objects when they were unaware that their hands were in the photographed set. It was concluded that recognition of even this highly familiar stimulus is dependent upon selection of the appropriate identifying cues, and that this process depends on expectation.

Hemispheric differences in picture-word interference

Abstract In a picture-word version of the Stroop task, 30 right-handed subjects were tested under each of six conditions in which a picture alone or a picture plus a word were presented to the left, the right, or both hemispheres. In two additional conditions the picture was presented to the right hemisphere and the word was simultaneously presented to the left hemisphere, or vice versa. For all conditions, subjects were instructed to name the picture only, as rapidly as possible. Picture naming times were significantly slower for the conditions in which the pictures were accompanied by words than in the respective picture alone conditions. Moreover, simultaneous presentation of a picture and a word to both hemispheres resulted in greater interference (slower picture naming times) than did the simultaneous presentation of the picture and the word to either the left hemisphere alone or the right hemisphere alone. The latter two conditions, in turn, resulted in significantly more interference than did the simultaneous presentation of the picture to one hemisphere and the word to the other hemisphere. This pattern of results suggests that the Stroop effect obtained under normal circumstances is in large part a function of the interference caused by the simultaneous processing of items in the same hemisphere. In contrast to hemispheric differences reported for the color-word Stroop task, the effect of presenting a picture and word simultaneously to the right hemisphere did not differ reliably from that of presenting a picture and word to the left hemisphere. The failure to replicate this aspect of the color-word Stroop is attributed to differences in the abilities of the two hemispheres to process the respective target items (the color or the picture) of the two tasks.

Critical periods for the transmission of tactual information.

There is good evidence for critical periods in the development of sensory processes (particularly vision and hearing) and language functions. If appropriate experience is absent during these critical periods, later performance is impaired. This principle is of importance to designers of devices which use the skin as an alternative channel of communication for the blind of the deaf. The implications are that: (a) Some promising devices may have been prematurely abandoned because they were tested on adults rather than children. (b) Tactile devices should be evaluated in studies with children who have not yet passed through the critical period for touch and language development. It is argued that early exposure to a tactile transformation of speech (for example) might provide the profoundly deaf with two significant advantages. Firstly, early exposure increases the chance that the cutaneous system will develop neural connections appropriate to the handling of the transformed speech signal. In other words, tactile sensitivity can be optimized. Secondly, early exposure to language as a process associated with the cutaneous system (rather than the auditory system) might favour the development of cortical connections consistent with the sensory substitution system. Such plasticity might no longer exist when the critical period has passed.

Different orientations of sub-two-point threshold tactile stimuli can be discriminated

The two points of an esthesiometer were touched on the axes of a cross drawn on the inside surface of subjects’ forearms. One axis was drawn transversely (Line AB) and the other proximodistally (Line CD). Esthesiometer points (delivered simultaneously either on Line AB or CD) were always equidistant from the center of the cross, but they were reduced in separation distance until the two points felt like one (two-point threshold condition). A further condition consisted of the simultaneous delivery of two-point stimuli on Lines AB and CD in random order. Point separation was reduced until subjects could no longer report whether the two points touched were on Line AB or Line CD (orientation discrimination threshold). The latter threshold was found to be significantly lower than the two-point threshold, and this result was interpreted as support for the hypothesis that these two measures of tactile resolution take advantage of different properties of cutaneous receptive fields.

Ranking of Crime Seriousness in Papua New Guinea: The Effects of Urbanization

Subjects, 46 male and 41 female Papua New Guineans who resided in Port Moresby and its suburbs, ranked 19 crimes according to relative seriousness. These ranks were compared with a ranking of the same crimes according to the penalties prescribed by the Papua New Guinean legal system and with data previously obtained from rural subjects. The overall urban mean ranks correlated significantly with legal ranks as did the male and female urban ranks separately. Urban subjects more closely approximated the legal ranks than did rural subjects, and these two sets of ranks were also more in agreement than were rural and legal ranks when the crimes were considered in 4 categories-against people, against property, sexual crimes, and victimless crimes. The ranking of crimes changed with increased exposure to urban culture, most particularly for victimless and sexual crimes which were ranked less disparately in relation to the law as a function of longer residence in an urban area. The greatest mean differences in ranks between the law and rural subjects occurred for adultery and indecent exposure. These differences were maintained for subjects with minimal exposure to urban culture (1-5 years), but were not found for urban dwellers of longer standing. Those who had resided in an urban area for more than 10 years provided ranks which differed most from the legal ranks for shoplifting and drunk driving. Factors that may have contributed to this shift in attitude towards relative crime with urbanization are discussed.