No abstract

Previous research has demonstrated that the degree of aesthetic pleasure a person experiences correlates with the activation of reward functions in the brain. However, it is unclear whether different affective qualities and the perceptions of beauty that they evoke correspond to specific areas of brain activation. Major and minor musical keys induce two types of affective qualities--bright/happy and dark/sad--that both evoke aesthetic pleasure. In the present study, we used positron emission tomography to demonstrate that the two musical keys (major and minor) activate distinct brain areas. Minor consonant chords perceived as beautiful strongly activated the right striatum, which has been assumed to play an important role in reward and emotion processing, whereas major consonant chords perceived as beautiful induced significant activity in the left middle temporal gyrus, which is believed to be related to coherent and orderly information processing. These results suggest that major and minor keys, both of which are perceived as beautiful, are processed differently in the brain.

Two identical visual objects moving across each other in a two-dimensional display can be perceived as either streaming through or bouncing off each other. The bouncing event percept is promoted by the presentation of a brief sound at the point of coincidence of the two objects. In this study, we examined the effect of the presence of a moving object near the two objects as well as the brief sound on the stream/bounce event perception. When both the nearby moving object and brief sound were presented, a streaming event, not a bouncing event, was robustly perceived (experiment 1). The percentage of the streaming percept was also systematically affected by the proximity of the nearby object (experiment 2). These results suggest that the processing of intramodal grouping between a nearby moving object and either of the two objects in the stream/bounce display interferes with crossmodal (audiovisual) processing. Moreover, we demonstrated that, depending on the trajectory of the nearby moving object, the processing of intramodal grouping can promote the bouncing percept, just as crossmodal processing does (experiment 3).

With few exceptions, the sound-induced bias toward bouncing characteristic of the stream/bounce effect has been demonstrated via subjective responses, leaving open the question whether perceptual factors, decisional factors, or some combination of the two underlie the illusion. We addressed this issue directly, using a novel stimulus and signal detection theory to independently characterize observers' sensitivity (d') and criterion (c) when discriminating between objective streaming and bouncing events in the presence or absence of a brief sound at the point of coincidence. We first confirmed that sound-induced motion reversals persist despite rendering the targets visually distinguishable by differences in texture density. Sound-induced bouncing persisted for targets differing by as many as nine just-noticeable-differences (JNDs). We then exploited this finding in our signal detection paradigm in which observers discriminated between objective streaming and bouncing events. We failed to find any difference in sensitivity (d') between sound and no-sound conditions, but we did observe a significantly more liberal criterion (c) in the sound condition than the no-sound condition. The results suggest that the auditory-induced bias toward bouncing in this context is attributable to a sound-induced shift in criterion implicating decisional processes rather than perceptual processes determining responses to these displays.

The area near the head of Lake Wakatipu lies between the Livingstone Fault to the west, and the Otago Schist terrane to the east. The area is divided into three major tectonic slices or subareas by north-striking faults. A eastward-younging sequence of Caples Group strata in the western-subarea is subdivided into four informal units consisting predominantly of volcanogenic sediments, feldspathic sandstone, tuff and tuffaceous sandstone, and grey sandstone and slate respectively. The Greenstone Ultramafite Belt, which separates the western subarea from the middle subarea, is interpreted as a tectonic melange of serpentinite, metagabbro, mafic volcanic and metasedimentary rocks. The synclinal Bold Peak unit, predominantly rhythmically alternating green sandstone and slate, occupies the middle subarea and is separated by an important inferred fault, the West Wakatipu Fault, from the eastern subarea which represents the western limit of the Haast Schist of Central Otago.Five metamorphic zones are recognised. Distinctive minerals are: Zone I: prehnite±pumpellyite; Zone II: Lawsonite with albite, pumpellyite, and chlorite without actinolite; Zone Ilia: green pumpellyite, actinolite, and rare (relict?) blue amphibole; Zone IIIb: colourless pumpellyite; Zone IV: actinolite without pumpellyite. Metamorphic grade in the area does not increase continuously from west to east into the Haast (Otago) Schist terrane.Twenty-nine new chemical analyses of mafic volcanogenic, pelitic, psammitic, ferruginous and siliceous rocks are presented for the area, and their characteristics are discussed. Psammitic and pelitic rocks of this area are distinctly low in Si02, and high in Al20a, total iron, MgO, and CaO as compared with those from Alpine facies rocks of the New Zealand Geosyncline. These characteristics are shared with Hokonui facies rocks flanking the south-west side of the Haast Schist terrane. Potash/soda ratios in the mafic volcanogenic rocks are low as is expected for the eastern or oceanward flank of an ancient arc structure. Other chemical characteristics, including those of relict clinopyroxenes, suggest an original range from alkalic to tholeiitic compositions for the mafic volcanics. FeO/Fe203 ratio of the analysed rocks of this area are characteristically low.