The rat’s long-term preference for complexity in its environment

Denny, Michael S.

doi:10.3758/bf03213439

Cited by 33 publications

(11 citation statements)

References 15 publications

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“…The finding that rats in the novelty condition spent more time eating than those in the complexity condition has parallels with findings that unenriched rats spend more time feeding than those in enriched cages (Denny, 1975;Fiala et al, 1977;Townsend, 1997;Zaias et al, 2008). The more limited set of alternative activities available in the novelty condition may have promoted increased eating behaviour, as may have the larger amount of time spent under the food hopper (which was positively correlated with the total time spent feeding).…”

Section: Discussionsupporting

confidence: 64%

The effects of enrichment novelty versus complexity in cages of group-housed rats (Rattus norvegicus)

Abou-Ismail

Mendl

2016

Applied Animal Behaviour Science

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). Tel. 002 (0)162557996Fax. 002 (0)502379952 Highlights  The study examined whether effects of environmental enrichment are due to novelty or complexity.  Behavioural, performance and pathological indicators of welfare were used.  The effects of enrichment are mainly due to complexity of the cages by multiple items.  The type of environmental enrichment protocol affects welfare of laboratory rats. AbstractAlthough experimental work on environmental enrichment has answered many important questions, it is not yet known whether beneficial effects of enrichment are more strongly influenced by regular provision of novel objects, or by the diversity of objects present at any one time. In a five-replicate study, 80 newly weaned male Wistar rats were housed in groups of four in: a 'novelty' condition (NC) in which five copies of the same object were provided in the home cage during the first week of the study followed by five copies of a different, novel, object over each of the next 4 weeks; a 'complexity' condition (CC) in which one example of each of the five objects used in NC was always present in the cage across the 5-week study period. Behaviour was collected in two 2-hrs sessions every week, once during the light phase of the light/dark cycle and once during the dark phase. Body weight and weight gain were measured over the five weeks and organ weights were recorded postmortem. Rats in the CC displayed elevated levels of measures suggestive of improved welfare such as sleep, enrichment-directed behaviour, enrichment contact, weight gain and relative thymus weight, and decreased levels of indicators denoting poor welfare including aggression, awake-non active and audible vocalizations. It appears that CC may have the potential to increase the frequency and diversity of behaviours, to express different types of behaviour when desired, and to augment the ability of the animals to exert some control over their environment, findings that may improve their welfare. Provision of novelty per se in the absence of diversity of objects at any one time seems to be less beneficial. Order (replicate) effects in the NC group indicated that responses of the animals towards the enrichment regimen appeared to depend on the type of object supplied, thus drawing attention to the importance of object characteristics when designing enrichment protocols for laboratory animals.

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Section: Discussionsupporting

confidence: 64%

The effects of enrichment novelty versus complexity in cages of group-housed rats (Rattus norvegicus)

Abou-Ismail

Mendl

2016

Applied Animal Behaviour Science

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“…However, even in the case of SC rats, which were reared in standard laboratory conditions, our results actually are not in agreement with those found in literature: in most studies, the rats showed a strong preference for complexity (e.g. Baker & Franken, 1967;Dember, Earl, & Paradise, 1957;Denny, 1975) or, at least, a preference for a moderate or optimal level of complexity (e.g. Berlyne, 1960;Dutch & Brown, 1971, May, 11968).…”

Section: Discussioncontrasting

confidence: 56%

“…We should stress that this observation is in conflict with Denny's (1975) observations on isolated rats: Denny noticed, first, that a preference for complexity exists and, second, that this preference was stronger during the daytime. These results were interpreted by him as a shelter/relaxation seeking response elicited by the number or complexity of elements in the complexity area.…”

Section: Discussioncontrasting

confidence: 47%

Effects of rearing in different environments on subsequent environmental preference in rats

Will¹,

Pallaud²,

Ungerer³

et al. 1979

Developmental Psychobiology

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Environmental preference of male rats reared during 2 months after weaning either in a complex and changing environment (EC) or in empty laboratory cages (SC) was assessed in 4 different experiments. For 2 weeks after differential rearing, rats were placed in groups of 6 in testing cages which were divided into 2 compartments with communicating holes. One of these compartments was empty; the other contained 6 objects (complex compartment). Daily, 3 objects were moved from 1 compartment to the other and replaced by new ones. The preference for any of the compartments was chiefly assessed by the localization of feces (Experiments I and II) and directly by the localization of the animals through videorecording (Experiments III and IV). Both EC and SC rats showed a significant preference for the empty compartment during both light and dark portions of the daily cycle, but particularly during the light portion.Moreover, EC and SC animals differed from one another in that the SC rats showed a stronger preferences for the empty compartment than the EC rats, especially when active. General preference for the empty compartment seemed to diminish slowly, but EC and SC rats tended to remain distinct in habitat selection, at least during the period tested. This behavioral difference, tentatively interpreted in terms of neophobia, might constitute a possible mechanism for automaintenance of differential rearing effects.

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“…This may help explain why, on average, the rats (n ¼ 20) spent four times longer in a 'high' complexity environment (highest density and diversity of chains hanging from cage roof) than in a medium or low complexity environment, engaging in significantly higher rates of ambulation and resting activity (Denny 1975). Male Wistar rats kept in a standard cage with (n ¼ 10) and without (n ¼ 10) a propylene cage insert strongly preferred the altered cage to the empty one in two-way choice tests lasting 8 h for each subject (Townsend 1997).…”

Section: B Environmental Complexitymentioning

confidence: 99%

Laboratory environments and rodents' behavioural needs: a review

Balcombe

2006

Lab Anim

150

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SummaryLaboratory housing conditions have significant physiological and psychological effects on rodents, raising both scientific and humane concerns. Published studies of rats, mice and other rodents were reviewed to document behavioural and psychological problems attributable to predominant laboratory housing conditions. Studies indicate that rats and mice value opportunities to take cover, build nests, explore, gain social contact, and exercise some control over their social milieu, and that the inability to satisfy these needs is physically and psychologically detrimental, leading to impaired brain development and behavioural anomalies (e.g. stereotypies). To the extent that space is a means to gain access to such resources, spatial confinement likely exacerbates these deficits. Adding environmental 'enrichments' to small cages reduces but does not eliminate these problems, and I argue that substantial changes in housing and husbandry conditions would be needed to further reduce them.

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The rat’s long-term preference for complexity in its environment

Cited by 33 publications

References 15 publications

The effects of enrichment novelty versus complexity in cages of group-housed rats (Rattus norvegicus)

The effects of enrichment novelty versus complexity in cages of group-housed rats (Rattus norvegicus)

Effects of rearing in different environments on subsequent environmental preference in rats

Laboratory environments and rodents' behavioural needs: a review

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