Septal influences on operant responding in the rat.

The afferent and efferent connections of the septum with the hippocampus (fornix) of with the hypothalamus and lower brain stem (medial forebrain bundle) were transected by means of an encephalotome near the point where these pathways enter or leave the septal area. A transection of the fornix that produced minimal direct damage to cellular components of the septum of hippocampus reproduced the effects of large septal lesions on responding in several temporally defined paradigms that involve periods of response suppression (differential reinforcement of low rates, discriminated Sidman avoidance, fixed interval). Transection of the medial forebrain bundle fibers that interconnect the septum with the hypothalamus and lower brain stem did not affect behavior in any of these paradigms. These observations should be veiwed in the context of the results of earlier investigations which demonstrated that transection of the medial forebrain bundle reproduces several other components of the septal lesion syndrome.     

Some behavioral effects of transecting ventral or dorsal fiber connections of the septum in the rat.

The behavioral effects of large electrolytic lesions in the septal area were compared with those of knife cuts that severed the ventral or dorsal connections of this structure. Rats with septal lesions lost weight and were transiently hyperdipsic. Ventral cuts produced similar effects, but dorsal cuts did not. All three operations decreased the latency to eat in a novel environment, increased the intake of sweetened milk, enhanced acquisition of a food-rewarded running response, and facilitated acquisition of a shuttle box avoidance response, The lesion, but neither of the knife cuts, reduced the effects of punishment and impaired the acquisition of a one-way avoidance response.     

The effects of increasing familiarity on infants' reactions to adult strangers

The influence of the presence and novelty of an adult stranger on the reactions of 12-mo-old infants was investigated. Subjects were placed near their mothers in a room containing a new toy and either the same, a different, or no adult stranger for 8 4-min trials. Results indicated that the Same-Adult Group spent more time near the adult, less time near and touching their mothers, and more time near and touching the toys than the Different-Adult Group. These trends emerged as the trials progressed, and evidenced the Same-Adult Group's growing familiarity with the adult. The No-Adult Group spent less time near or touching their mothers and more time near or touching the toys than the Different-Adult Group, but did not differ from the Same-Adult Group on these responses. The findings suggest that fearful or cautious reactions to adult strangers disappear rapidly as the adult becomes familiar and point to the value of studying the process whereby the infant becomes familiar with new people.     

Triadic decision making in lexical memory

Word and category recognition was investigated in the context of other stimuli, where the semantic distance relationships among the stimuli were derived from multidimensional scaling. On each trial, three horizontal strings of letters were presented. In the word condition, a positive response was required when the three strings formed three words; in the category condition, a positive response was required when the three strings formed words belonging to the same category. The results indicated that: (a) category decisions take about 150-200 msec longer than do word decisions, (b) word decisions are facilitated by a common categorical membership but semantic distances within the category are relatively unimportant, and (c)within-category semantic distances systematically altered response time for the category condition. It was hypothesized that semantic distance relationships may be sensitized for categorical decisions, but that only large semantic distances function effectively for word decisions.     

Voice recognition by matching to sample

Voice recognition was assessed by a matching to sample procedure in 30 right-handed adults with normal hearing. The subject was required to indicate which of three voices speaking a nonsense syllable matched the speaker of a sample vowel. Subjects were able to recognize voices with reasonable accuracy, but there were no significant differences as a function of ears or practice, and performance was not markedly affected by knowledge of results or mode of response. There was a significant difference as a function of the temporal position of the matching voice, with recognition being most accurate when the matching voice was first and least accurate when it was third. Further research is necessary to determine whether voice recognition should be classified as the type of verbal ability associated with the cerebral hemisphere dominant for speech, or whether it is the type of nonverbal auditory ability associated with the nonspeech hemisphere.This research was supported in part by grant MA-1652 from the Medical Research Council of Canada.     

Adaptation and counteradaptation to complex optical distortion

The optical distortion caused by wearing a facemask in water magnifies the angular size of objects and reduces their optical distance. However, objects generallyappear to be further than their optical distance, with the result that points in the left part of the visual field are apparently displaced to the left, and those on the right to the right. Experiments on hand-eye coordination under water showed that adaptation to one aspect of the distortion produced some counteradaptation to complementary aspects: adaptation to distance produced increased lateral distortion, and adaptation to one side of the lateral distortion produced increased distortion on the opposite side. Nevertheless, “trading” was incomplete, and some overall adaptation of the visual metric occurred.     

A content semantics for quantified relevant logics. II

In part I, we presented an algebraic-style of semantics, which we called “content semantics,” for quantified relevant logics based on the weak systemBBQ. We showed soundness and completeness with respect to theunreduced semantics ofBBQ. In part II, we proceed to show soundness and completeness for extensions ofBBQ with respect to this type of semantics. We introducereduced semantics which requires additional postulates for primeness and saturation. We then conclude by showing soundness and completeness forBB ^d Q and its extentions with respect to this reduced semantics.     

The access of relevant information for solving problems

Two issues were investigated concerning the retrieval of recently acquired relevant information for solving riddle problems. First, although earlier research indicated that problem solvers often fail to retrieve relevant information unless they are explicitly informed of its relevance, Bowden (1985) suggested that uninformed subjects would benefit greatly from additional problem-solving time. In two experiments, we found that uninformed subjects solved more problems than did subjects who did not receive the information, but a simple model attributed this difference to these uninformed subjects "catching on" to the information's relevance after solving some problems. Second, the retrieval characteristics were examined by varying the proportion of problems for which clues were given. Informed subjects given clues for only half of the problems benefited (though perhaps not fully) from being informed, without incurring any cost from being misdirected on the unclued problems. The discussion focuses on some ways in which accessing relevant information may affect problem solving.