title: An investigation of two behavioural economic approaches to evaluating reinforcer value

authors: Lim, Bee Lan Linda

subjects: Behaviour economics

abstract: This study compares two approaches for comparing the value of two different reinforcers. The own-price demand method compares the changes in consumption of the reinforcers resulting from increases in the number of responses required to gain access to the reinforcers. Experiment 1 assessed own-price demand for two reinforcers. Six hens responded under increasing fixed-ratio schedules when either wheat or puffed wheat was delivered for key-pecking. The quantity consumed (measured as either numbers of reinforcers obtained or weight of food consumed) was plotted against the FR size on log-log coordinates to give the own-price demand functions. Three functions were fitted to the data and all described the data well. The parameter values from Hursh’s (1988) and Hursh and Winger’s (1995) equations were generally consistent with wheat being the preferred reinforcer data when derived from the weight of food consumed. Those derived from number of reinforcers were inconsistent. The essential value, α, from the equation proposed by Hursh and Silberberg (2008), when k was fixed at 6.5, were smaller when weight was used and were weight was used and were larger when number of reinforcers was used as the consumption measures and so suggested the essential value changed. These data show that the outcome is affected by how the consumption is measured. It seems that that the above models were similar. The cross-price demand method examines the divergence of the cross-point of two demand functions. In Experiment 2 assessed the cross-point using the same six hens responding under concurrent fixed-ratio fixed-ratio schedules over nine pairs of schedules: FR1/FR256, FR8/FR32, FR128/FR2, FR4/FR64, FR256/FR1, FR32/FR8, FR2/FR128, FR16/FR16 and FR64/FR4. In Condition 1 both schedules gave access to wheat, in Condition 2 both gave puffed wheat, and in Condition 3 one gave wheat and the other puffed wheat. The numbers of each reinforcer obtained and weight of each food consumed were plotted as functions of the left fixed-ratio values to give the cross-price demand functions. When the two reinforcers were identical the cross point tended to be around the ratio used for the equal schedules session (16) with both number of reinforcers and weight of food.. When the two reinforcers differed the cross point for most hens moved to higher ratio when weight of food consumed was used, suggesting that wheat was more valued than puffed wheat for these hens. This was not so for number of reinforcers. Both experiments show that how the consumption was assessed affected the conclusions from that method. Overall the cross-price demand analysis appeared to be the easier to interpret.

text: An investigation of two behavioural economic approaches to evaluating reinforcer value This study compares two approaches for comparing the value of two different reinforcers. The own-price demand method compares the changes in consumption of the reinforcers resulting from increases in the number of responses required to gain access to the reinforcers. Experiment 1 assessed own-price demand for two reinforcers. Six hens responded under increasing fixed-ratio schedules when either wheat or puffed wheat was delivered for key-pecking. The quantity consumed (measured as either numbers of reinforcers obtained or weight of food consumed) was plotted against the FR size on log-log coordinates to give the own-price demand functions. Three functions were fitted to the data and all described the data well. The parameter values from Hursh’s (1988) and Hursh and Winger’s (1995) equations were generally consistent with wheat being the preferred reinforcer data when derived from the weight of food consumed. Those derived from number of reinforcers were inconsistent. The essential value, α, from the equation proposed by Hursh and Silberberg (2008), when k was fixed at 6.5, were smaller when weight was used and were weight was used and were larger when number of reinforcers was used as the consumption measures and so suggested the essential value changed. These data show that the outcome is affected by how the consumption is measured. It seems that that the above models were similar. The cross-price demand method examines the divergence of the cross-point of two demand functions. In Experiment 2 assessed the cross-point using the same six hens responding under concurrent fixed-ratio fixed-ratio schedules over nine pairs of schedules: FR1/FR256, FR8/FR32, FR128/FR2, FR4/FR64, FR256/FR1, FR32/FR8, FR2/FR128, FR16/FR16 and FR64/FR4. In Condition 1 both schedules gave access to wheat, in Condition 2 both gave puffed wheat, and in Condition 3 one gave wheat and the other puffed wheat. The numbers of each reinforcer obtained and weight of each food consumed were plotted as functions of the left fixed-ratio values to give the cross-price demand functions. When the two reinforcers were identical the cross point tended to be around the ratio used for the equal schedules session (16) with both number of reinforcers and weight of food.. When the two reinforcers differed the cross point for most hens moved to higher ratio when weight of food consumed was used, suggesting that wheat was more valued than puffed wheat for these hens. This was not so for number of reinforcers. Both experiments show that how the consumption was assessed affected the conclusions from that method. Overall the cross-price demand analysis appeared to be the easier to interpret.

year: 2010

title: Human impact on the McMurdo Dry Valley soils of Antarctica: Extending the limits of DNA detection

authors: Wakerley, Georgia L.J.

subjects: Antarctica

abstract: Antarctica is commonly regarded as the most pristine place on Earth and is safeguarded by the Antarctic Treaty System (ATS). The ATS designates the continent as a “natural reserve, devoted to peace and science” and sets out environmental principles regulating human activities. The obligations under the ATS include providing environmental impact assessments and leaving the environment minimally impacted after all operations. The associated human footprint inevitably increases as human activity increases in intensity and diversity on the continent. The human footprint is not clearly defined, and most investigation has focused on visible disturbances of physical (e.g., soil disturbance) and chemical (e.g., hydrocarbon spills) nature. The unseen human footprint remains to be investigated and quantified, which includes released genetic materials and human-associated microorganisms. Given the extremely low biomass in most of terrestrial Antarctica, these materials' presence can be a reliable indicator of human presence and activities.
As part of New Zealand’s effort to carry out an evidence-based risk assessment of the McMurdo Dry Valley ecosystem (DryVER project), this research quantified human impact, in the form of DNA released from humans and human-associated microbiota, across spatial and temporal scales. This project was part of the MBIE grant entitled “Evidence-based Risk Assessment of the McMurdo Dry Valley Ecosystem”. Areas of human activity, including seasonal field camps and facilities zones, were selected as sampling sites in the McMurdo Dry Valleys (MDVs), from which soil samples were collected. Human-specific genetic and microbial markers were used with digital PCR to quantify human presence at the lowest possible detection limit across spatial scales. A marker targeting a human MT-CYB gene region was the best marker for detecting and predicting human trace up to 1 km from a highly occupied site. Human impact derived from mtDNA was accumulative with occupancy and greatest closest to a campsite. A marker targeting 16S rRNA of Bacteroides dorei, a human-associated gut bacterium, was used to detect faecal trace. The faecal signal was generally localised to the toilet area of a camp and was too low to predict the distance of detectable signal, regardless of the intensity of occupancy. A DNA longevity experiment was established in situ in Miers Valley to investigate DNA persistence in a cold desert across temporal scales. The results from this experiment demonstrated that intracellular and extracellular DNA remained detectable with endpoint PCR for at least two years. DNA persistence was not significantly affected by soil sterility or UV exposure but did accumulate damage over time.
The direct outcome of this research will be a review of the environmental management systems in place, namely the McMurdo Dry Valleys Antarctic Specially Managed Area (ASMA) Management Plan. Better management will safeguard the unique MDV ecosystems by using the best practice to minimise anthropogenic impact and strengthen New Zealand’s stewardship over the Ross Dependency as one of the original 12 signatories to the Antarctic Treaty.

text: Human impact on the McMurdo Dry Valley soils of Antarctica: Extending the limits of DNA detection Antarctica is commonly regarded as the most pristine place on Earth and is safeguarded by the Antarctic Treaty System (ATS). The ATS designates the continent as a “natural reserve, devoted to peace and science” and sets out environmental principles regulating human activities. The obligations under the ATS include providing environmental impact assessments and leaving the environment minimally impacted after all operations. The associated human footprint inevitably increases as human activity increases in intensity and diversity on the continent. The human footprint is not clearly defined, and most investigation has focused on visible disturbances of physical (e.g., soil disturbance) and chemical (e.g., hydrocarbon spills) nature. The unseen human footprint remains to be investigated and quantified, which includes released genetic materials and human-associated microorganisms. Given the extremely low biomass in most of terrestrial Antarctica, these materials' presence can be a reliable indicator of human presence and activities.
As part of New Zealand’s effort to carry out an evidence-based risk assessment of the McMurdo Dry Valley ecosystem (DryVER project), this research quantified human impact, in the form of DNA released from humans and human-associated microbiota, across spatial and temporal scales. This project was part of the MBIE grant entitled “Evidence-based Risk Assessment of the McMurdo Dry Valley Ecosystem”. Areas of human activity, including seasonal field camps and facilities zones, were selected as sampling sites in the McMurdo Dry Valleys (MDVs), from which soil samples were collected. Human-specific genetic and microbial markers were used with digital PCR to quantify human presence at the lowest possible detection limit across spatial scales. A marker targeting a human MT-CYB gene region was the best marker for detecting and predicting human trace up to 1 km from a highly occupied site. Human impact derived from mtDNA was accumulative with occupancy and greatest closest to a campsite. A marker targeting 16S rRNA of Bacteroides dorei, a human-associated gut bacterium, was used to detect faecal trace. The faecal signal was generally localised to the toilet area of a camp and was too low to predict the distance of detectable signal, regardless of the intensity of occupancy. A DNA longevity experiment was established in situ in Miers Valley to investigate DNA persistence in a cold desert across temporal scales. The results from this experiment demonstrated that intracellular and extracellular DNA remained detectable with endpoint PCR for at least two years. DNA persistence was not significantly affected by soil sterility or UV exposure but did accumulate damage over time.
The direct outcome of this research will be a review of the environmental management systems in place, namely the McMurdo Dry Valleys Antarctic Specially Managed Area (ASMA) Management Plan. Better management will safeguard the unique MDV ecosystems by using the best practice to minimise anthropogenic impact and strengthen New Zealand’s stewardship over the Ross Dependency as one of the original 12 signatories to the Antarctic Treaty.

year: 2024-05-21

title: Māori & Psychology Research Unit Annual Report 2015

authors: Waitoki, Waikaremoana

abstract: The Māori and Psychology Research Unit (MPRU) was established in August of 1997. The Unit acts as a catalyst and support network for enhancing research concerning the psychological needs, aspirations, and priorities of Māori people. The MPRU is well situated to draw together skilled and experienced interdisciplinary research groups by networking and establishing working relationships with staff and students within the School of Psychology, the Faculty of Arts and Social Sciences, the wider University and general community.

text: Māori & Psychology Research Unit Annual Report 2015 The Māori and Psychology Research Unit (MPRU) was established in August of 1997. The Unit acts as a catalyst and support network for enhancing research concerning the psychological needs, aspirations, and priorities of Māori people. The MPRU is well situated to draw together skilled and experienced interdisciplinary research groups by networking and establishing working relationships with staff and students within the School of Psychology, the Faculty of Arts and Social Sciences, the wider University and general community.

year: 2015