It is often assumed that emotional events are remembered in great clarity and detail. This thesis begins with a review of the literature on memory enhancement by emotional material. This enhancement may involve mechanisms that are psychologically and neurobiologically distinct from the mechanisms usually employed in memory for neutral material, such as modulation of consolidation by emotional arousal via noradrenaline action in the amygdala. Theoretically, pharmacological manipulation of noradrenaline by methylphenidate and benzodiazepines should affect the function of specialised 'emotional memory' mechanisms, altering the balance of emotional and neutral material remembered. A set of four double blind, placebo controlled experiments were designed to investigate this theory. Each was carried out with three groups of 16 healthy human volunteers. Experiment 1 produced some evidence that both 1.5mg lorazepam and 40mg methylphenidate reduced the mnemonic advantage of emotional sections of a story. Experiment 2 compared diazepam (15mg) with placebo and propranolol (80mg) (a ?-blocker which has been reported to impair emotional memory) on two new tasks. Diazepam left implicit memory intact, but impaired explicit memory, particularly for emotional material. In Experiment 3 both diazepam (15mg) and methylphenidate (40mg) altered relative levels of recall for emotional and neutral pictures. In Experiment 4 diazepam (10mg) clearly impaired fear conditioning. However there was no evidence that diazepam (10mg) or methylphenidate (40mg) affected emotional memory during consolidation. Taken together these studies provide evidence for a pharmacological dissociation of fear conditioning and perceptual priming. There was some evidence that benzodiazepines disproportionately impaired explicit emotional memory. However these effects were subtle. Methylphenidate increased the relative amount of emotional material retained on some measures, and decreased or left it unchanged in others. This may be due to differing levels of arousal. A central issue throughout the thesis was the difficulty of separating the 'emotional memory' mechanism from other co-occurring mnemonic properties of emotional stimuli. These may mask effects of the pharmacological manipulations that would be informative to any theory of 'emotional memory'.

In the environmental context (EC)-dependent memory literature, it is not clear whether global EC studies can provide results and conclusions that can be generalized to local EC phenomena and vice-versa. So far, no systematic effort has been made to distinguish between the two types of EC. The main aim of this thesis is to determine whether global and local environmental context manipulations, as employed in the literature, affect free recall and recognition tests in a comparable manner. The first two experiments deal with issues of stimulus presentation and encoding instructions. Their results indicate that the most efficient manner to present stimulus words at encoding is to present words singly (as opposed to word pairs) and direct subjects to process them in an item specific (as opposed to relational) manner. In subsequent experiments, a modified version of the remember/know procedure (Tulving, 1985) is applied to distinguish between recollection and familiarity processes at retrieval. Analyses are presented both from the standard perspective and from the dual-process perspective. Experiments 3 and 4 tested recognition memory and employed a local EC manipulation. Experiment 5 also tested recognition memory, but employed a global EC manipulation. Experiment 6 tested free recall and employed a local EC manipulation. Finally, Experiments 7 and 8 tested free recall and employed a global EC manipulation. The pattern of results provided by all the experiments led to the conclusion that global EC experiments and local EC experiments produce substantially different outcomes and, consequently, generalizations from one type of study to the other should be treated with caution. Suggestions for further research stemming from these results are presented in Chapter 8.

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Time-code theories of temporal memory argue that memories are tagged with dedicated temporal information which assist temporal judgments (e.g., G. D. A. Brown & Chater, 2001). Though this account is studied mainly with short-term memory paradigms, some models propose such information is available across time periods. This thesis investigates whether intrinsic time information may facilitate temporal judgments at longer spans, using long-term memory (LTM) paradigms and investigations of remote memory. An alternative proposal is considered where we may rely on contextual associations to make these judgments. In LTM, judgments of recency on studied items were not more accurate for recently seen items, contrary to the time-code hypothesis. Neither do temporal ratios of the distance between items and the present relate to accuracy scores. Instead, the presence of a robust primacy effect, preserved when rehearsal is minimised, supports a reconstructive approach where the beginning of a list acts as a temporal landmark. This position is supported by experiments which establish that this landmark effect can be reproduced at other list positions, for events that follow that landmark, and that a corresponding recency effect is not evoked by greater expectation for the end of the list. Investigation of remote memory revealed that for a set of public events dating was no more accurate for individuals who had lived through them, and for those cases dating accuracy was unrelated to measures of primary memory, such as memorability or content knowledge, but did relate to where the event could be localised within a personal life period. A case series investigation of neurological patients suggests an interrelatedness between measures of order memory and forms of context memory, and presents cases where order memory is impaired despite a normal ability to estimate time durations. These studies are broadly supportive of a contextual account of temporal memory.

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